diff -r 490d5cc509ed -r cf61fcea0001 wp/wp-includes/functions.php
--- a/wp/wp-includes/functions.php	Tue Jun 09 11:14:17 2015 +0000
+++ b/wp/wp-includes/functions.php	Mon Oct 14 17:39:30 2019 +0200
@@ -78,6 +78,8 @@
  *
  * @since 0.71
  *
+ * @global WP_Locale $wp_locale
+ *
  * @param string   $dateformatstring Format to display the date.
  * @param bool|int $unixtimestamp    Optional. Unix timestamp. Default false.
  * @param bool     $gmt              Optional. Whether to use GMT timezone. Default false.
@@ -89,13 +91,7 @@
 	$i = $unixtimestamp;
 
 	if ( false === $i ) {
-		if ( ! $gmt )
-			$i = current_time( 'timestamp' );
-		else
-			$i = time();
-		// we should not let date() interfere with our
-		// specially computed timestamp
-		$gmt = true;
+		$i = current_time( 'timestamp', $gmt );
 	}
 
 	/*
@@ -104,15 +100,13 @@
 	 */
 	$req_format = $dateformatstring;
 
-	$datefunc = $gmt? 'gmdate' : 'date';
-
 	if ( ( !empty( $wp_locale->month ) ) && ( !empty( $wp_locale->weekday ) ) ) {
-		$datemonth = $wp_locale->get_month( $datefunc( 'm', $i ) );
+		$datemonth = $wp_locale->get_month( date( 'm', $i ) );
 		$datemonth_abbrev = $wp_locale->get_month_abbrev( $datemonth );
-		$dateweekday = $wp_locale->get_weekday( $datefunc( 'w', $i ) );
+		$dateweekday = $wp_locale->get_weekday( date( 'w', $i ) );
 		$dateweekday_abbrev = $wp_locale->get_weekday_abbrev( $dateweekday );
-		$datemeridiem = $wp_locale->get_meridiem( $datefunc( 'a', $i ) );
-		$datemeridiem_capital = $wp_locale->get_meridiem( $datefunc( 'A', $i ) );
+		$datemeridiem = $wp_locale->get_meridiem( date( 'a', $i ) );
+		$datemeridiem_capital = $wp_locale->get_meridiem( date( 'A', $i ) );
 		$dateformatstring = ' '.$dateformatstring;
 		$dateformatstring = preg_replace( "/([^\\\])D/", "\\1" . backslashit( $dateweekday_abbrev ), $dateformatstring );
 		$dateformatstring = preg_replace( "/([^\\\])F/", "\\1" . backslashit( $datemonth ), $dateformatstring );
@@ -130,7 +124,7 @@
 		if ( $timezone_string ) {
 			$timezone_object = timezone_open( $timezone_string );
 			$date_object = date_create( null, $timezone_object );
-			foreach( $timezone_formats as $timezone_format ) {
+			foreach ( $timezone_formats as $timezone_format ) {
 				if ( false !== strpos( $dateformatstring, $timezone_format ) ) {
 					$formatted = date_format( $date_object, $timezone_format );
 					$dateformatstring = ' '.$dateformatstring;
@@ -140,10 +134,10 @@
 			}
 		}
 	}
-	$j = @$datefunc( $dateformatstring, $i );
+	$j = @date( $dateformatstring, $i );
 
 	/**
-	 * Filter the date formatted based on the locale.
+	 * Filters the date formatted based on the locale.
 	 *
 	 * @since 2.8.0
 	 *
@@ -157,32 +151,95 @@
 }
 
 /**
- * Convert integer number to format based on the locale.
+ * Determines if the date should be declined.
+ *
+ * If the locale specifies that month names require a genitive case in certain
+ * formats (like 'j F Y'), the month name will be replaced with a correct form.
+ *
+ * @since 4.4.0
+ *
+ * @global WP_Locale $wp_locale
+ *
+ * @param string $date Formatted date string.
+ * @return string The date, declined if locale specifies it.
+ */
+function wp_maybe_decline_date( $date ) {
+	global $wp_locale;
+
+	// i18n functions are not available in SHORTINIT mode
+	if ( ! function_exists( '_x' ) ) {
+		return $date;
+	}
+
+	/* translators: If months in your language require a genitive case,
+	 * translate this to 'on'. Do not translate into your own language.
+	 */
+	if ( 'on' === _x( 'off', 'decline months names: on or off' ) ) {
+		// Match a format like 'j F Y' or 'j. F'
+		if ( @preg_match( '#^\d{1,2}\.? [^\d ]+#u', $date ) ) {
+			$months          = $wp_locale->month;
+			$months_genitive = $wp_locale->month_genitive;
+
+			foreach ( $months as $key => $month ) {
+				$months[ $key ] = '# ' . $month . '( |$)#u';
+			}
+
+			foreach ( $months_genitive as $key => $month ) {
+				$months_genitive[ $key ] = ' ' . $month . '$1';
+			}
+
+			$date = preg_replace( $months, $months_genitive, $date );
+		}
+	}
+
+	// Used for locale-specific rules
+	$locale = get_locale();
+
+	if ( 'ca' === $locale ) {
+		// " de abril| de agost| de octubre..." -> " d'abril| d'agost| d'octubre..."
+		$date = preg_replace( '# de ([ao])#i', " d'\\1", $date );
+	}
+
+	return $date;
+}
+
+/**
+ * Convert float number to format based on the locale.
  *
  * @since 2.3.0
  *
- * @param int $number   The number to convert based on locale.
- * @param int $decimals Optional. Precision of the number of decimal places. Default 0.
+ * @global WP_Locale $wp_locale
+ *
+ * @param float $number   The number to convert based on locale.
+ * @param int   $decimals Optional. Precision of the number of decimal places. Default 0.
  * @return string Converted number in string format.
  */
 function number_format_i18n( $number, $decimals = 0 ) {
 	global $wp_locale;
-	$formatted = number_format( $number, absint( $decimals ), $wp_locale->number_format['decimal_point'], $wp_locale->number_format['thousands_sep'] );
+
+	if ( isset( $wp_locale ) ) {
+		$formatted = number_format( $number, absint( $decimals ), $wp_locale->number_format['decimal_point'], $wp_locale->number_format['thousands_sep'] );
+	} else {
+		$formatted = number_format( $number, absint( $decimals ) );
+	}
 
 	/**
-	 * Filter the number formatted based on the locale.
+	 * Filters the number formatted based on the locale.
 	 *
-	 * @since  2.8.0
+	 * @since 2.8.0
+	 * @since 4.9.0 The `$number` and `$decimals` arguments were added.
 	 *
 	 * @param string $formatted Converted number in string format.
+	 * @param float  $number    The number to convert based on locale.
+	 * @param int    $decimals  Precision of the number of decimal places.
 	 */
-	return apply_filters( 'number_format_i18n', $formatted );
+	return apply_filters( 'number_format_i18n', $formatted, $number, $decimals );
 }
 
 /**
  * Convert number of bytes largest unit bytes will fit into.
  *
- * It is easier to read 1 kB than 1024 bytes and 1 MB than 1048576 bytes. Converts
+ * It is easier to read 1 KB than 1024 bytes and 1 MB than 1048576 bytes. Converts
  * number of bytes to human readable number by taking the number of that unit
  * that the bytes will go into it. Supports TB value.
  *
@@ -201,14 +258,17 @@
  */
 function size_format( $bytes, $decimals = 0 ) {
 	$quant = array(
-		// ========================= Origin ====
-		'TB' => 1099511627776,  // pow( 1024, 4)
-		'GB' => 1073741824,     // pow( 1024, 3)
-		'MB' => 1048576,        // pow( 1024, 2)
-		'kB' => 1024,           // pow( 1024, 1)
-		'B'  => 1,              // pow( 1024, 0)
+		'TB' => TB_IN_BYTES,
+		'GB' => GB_IN_BYTES,
+		'MB' => MB_IN_BYTES,
+		'KB' => KB_IN_BYTES,
+		'B'  => 1,
 	);
 
+	if ( 0 === $bytes ) {
+		return number_format_i18n( 0, $decimals ) . ' B';
+	}
+
 	foreach ( $quant as $unit => $mag ) {
 		if ( doubleval( $bytes ) >= $mag ) {
 			return number_format_i18n( $bytes / $mag, $decimals ) . ' ' . $unit;
@@ -252,8 +312,8 @@
 	// The most recent week start day on or before $day.
 	$start = $day - DAY_IN_SECONDS * ( $weekday - $start_of_week );
 
-	// $start + 7 days - 1 second.
-	$end = $start + 7 * DAY_IN_SECONDS - 1;
+	// $start + 1 week - 1 second.
+	$end = $start + WEEK_IN_SECONDS - 1;
 	return compact( 'start', 'end' );
 }
 
@@ -381,6 +441,7 @@
 
 	// Double serialization is required for backward compatibility.
 	// See https://core.trac.wordpress.org/ticket/12930
+	// Also the world will end. See WP 3.6.1.
 	if ( is_serialized( $data, false ) )
 		return serialize( $data );
 
@@ -490,10 +551,10 @@
  *
  * @since 1.5.0
  *
- * @see $wpdb
+ * @global wpdb $wpdb WordPress database abstraction object.
  *
  * @param string $content Post Content.
- * @param int $post_ID Post ID.
+ * @param int    $post_ID Post ID.
  */
 function do_enclose( $content, $post_ID ) {
 	global $wpdb;
@@ -527,6 +588,19 @@
 		}
 	}
 
+	/**
+	 * Filters the list of enclosure links before querying the database.
+	 *
+	 * Allows for the addition and/or removal of potential enclosures to save
+	 * to postmeta before checking the database for existing enclosures.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @param array $post_links An array of enclosure links.
+	 * @param int   $post_ID    Post ID.
+	 */
+	$post_links = apply_filters( 'enclosure_links', $post_links, $post_ID );
+
 	foreach ( (array) $post_links as $url ) {
 		if ( $url != '' && !$wpdb->get_var( $wpdb->prepare( "SELECT post_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE %s", $post_ID, $wpdb->esc_like( $url ) . '%' ) ) ) {
 
@@ -559,62 +633,6 @@
 }
 
 /**
- * Perform a HTTP HEAD or GET request.
- *
- * If $file_path is a writable filename, this will do a GET request and write
- * the file to that path.
- *
- * @since 2.5.0
- *
- * @param string      $url       URL to fetch.
- * @param string|bool $file_path Optional. File path to write request to. Default false.
- * @param int         $red       Optional. The number of Redirects followed, Upon 5 being hit,
- *                               returns false. Default 1.
- * @return bool|string False on failure and string of headers if HEAD request.
- */
-function wp_get_http( $url, $file_path = false, $red = 1 ) {
-	@set_time_limit( 60 );
-
-	if ( $red > 5 )
-		return false;
-
-	$options = array();
-	$options['redirection'] = 5;
-
-	if ( false == $file_path )
-		$options['method'] = 'HEAD';
-	else
-		$options['method'] = 'GET';
-
-	$response = wp_safe_remote_request( $url, $options );
-
-	if ( is_wp_error( $response ) )
-		return false;
-
-	$headers = wp_remote_retrieve_headers( $response );
-	$headers['response'] = wp_remote_retrieve_response_code( $response );
-
-	// WP_HTTP no longer follows redirects for HEAD requests.
-	if ( 'HEAD' == $options['method'] && in_array($headers['response'], array(301, 302)) && isset( $headers['location'] ) ) {
-		return wp_get_http( $headers['location'], $file_path, ++$red );
-	}
-
-	if ( false == $file_path )
-		return $headers;
-
-	// GET request - write it to the supplied filename
-	$out_fp = fopen($file_path, 'w');
-	if ( !$out_fp )
-		return $headers;
-
-	fwrite( $out_fp,  wp_remote_retrieve_body( $response ) );
-	fclose($out_fp);
-	clearstatcache();
-
-	return $headers;
-}
-
-/**
  * Retrieve HTTP Headers from URL.
  *
  * @since 1.5.1
@@ -625,7 +643,7 @@
  */
 function wp_get_http_headers( $url, $deprecated = false ) {
 	if ( !empty( $deprecated ) )
-		_deprecated_argument( __FUNCTION__, '2.7' );
+		_deprecated_argument( __FUNCTION__, '2.7.0' );
 
 	$response = wp_safe_remote_head( $url );
 
@@ -663,8 +681,8 @@
  * @since 2.3.0
  *
  * @see _http_build_query() Used to build the query
- * @see http://us2.php.net/manual/en/function.http-build-query.php for more on what
- *		http_build_query() does.
+ * @link https://secure.php.net/manual/en/function.http-build-query.php for more on what
+ *		 http_build_query() does.
  *
  * @param array $data URL-encode key/value pairs.
  * @return string URL-encoded string.
@@ -679,7 +697,7 @@
  * @since 3.2.0
  * @access private
  *
- * @see http://us1.php.net/manual/en/function.http-build-query.php
+ * @see https://secure.php.net/manual/en/function.http-build-query.php
  *
  * @param array|object  $data       An array or object of data. Converted to array.
  * @param string        $prefix     Optional. Numeric index. If set, start parameter numbering with it.
@@ -721,22 +739,39 @@
 }
 
 /**
- * Retrieve a modified URL query string.
- *
- * You can rebuild the URL and append a new query variable to the URL query by
- * using this function. You can also retrieve the full URL with query data.
- *
- * Adding a single key & value or an associative array. Setting a key value to
- * an empty string removes the key. Omitting oldquery_or_uri uses the $_SERVER
- * value. Additional values provided are expected to be encoded appropriately
- * with urlencode() or rawurlencode().
+ * Retrieves a modified URL query string.
+ *
+ * You can rebuild the URL and append query variables to the URL query by using this function.
+ * There are two ways to use this function; either a single key and value, or an associative array.
+ *
+ * Using a single key and value:
+ *
+ *     add_query_arg( 'key', 'value', 'http://example.com' );
+ *
+ * Using an associative array:
+ *
+ *     add_query_arg( array(
+ *         'key1' => 'value1',
+ *         'key2' => 'value2',
+ *     ), 'http://example.com' );
+ *
+ * Omitting the URL from either use results in the current URL being used
+ * (the value of `$_SERVER['REQUEST_URI']`).
+ *
+ * Values are expected to be encoded appropriately with urlencode() or rawurlencode().
+ *
+ * Setting any query variable's value to boolean false removes the key (see remove_query_arg()).
+ *
+ * Important: The return value of add_query_arg() is not escaped by default. Output should be
+ * late-escaped with esc_url() or similar to help prevent vulnerability to cross-site scripting
+ * (XSS) attacks.
  *
  * @since 1.5.0
  *
- * @param string|array $param1 Either newkey or an associative_array.
- * @param string       $param2 Either newvalue or oldquery or URI.
- * @param string       $param3 Optional. Old query or URI.
- * @return string New URL query string.
+ * @param string|array $key   Either a query variable key, or an associative array of query variables.
+ * @param string       $value Optional. Either a query variable value, or a URL to act upon.
+ * @param string       $url   Optional. A URL to act upon.
+ * @return string New URL query string (unescaped).
  */
 function add_query_arg() {
 	$args = func_get_args();
@@ -802,12 +837,12 @@
 }
 
 /**
- * Removes an item or list from the query string.
+ * Removes an item or items from a query string.
  *
  * @since 1.5.0
  *
  * @param string|array $key   Query key or keys to remove.
- * @param bool|string  $query Optional. When false uses the $_SERVER value. Default false.
+ * @param bool|string  $query Optional. When false uses the current URL. Default false.
  * @return string New URL query string.
  */
 function remove_query_arg( $key, $query = false ) {
@@ -820,6 +855,50 @@
 }
 
 /**
+ * Returns an array of single-use query variable names that can be removed from a URL.
+ *
+ * @since 4.4.0
+ *
+ * @return array An array of parameters to remove from the URL.
+ */
+function wp_removable_query_args() {
+	$removable_query_args = array(
+		'activate',
+		'activated',
+		'approved',
+		'deactivate',
+		'deleted',
+		'disabled',
+		'enabled',
+		'error',
+		'hotkeys_highlight_first',
+		'hotkeys_highlight_last',
+		'locked',
+		'message',
+		'same',
+		'saved',
+		'settings-updated',
+		'skipped',
+		'spammed',
+		'trashed',
+		'unspammed',
+		'untrashed',
+		'update',
+		'updated',
+		'wp-post-new-reload',
+	);
+
+	/**
+	 * Filters the list of query variables to remove.
+	 *
+	 * @since 4.2.0
+	 *
+	 * @param array $removable_query_args An array of query variables to remove from a URL.
+	 */
+	return apply_filters( 'removable_query_args', $removable_query_args );
+}
+
+/**
  * Walks the array while sanitizing the contents.
  *
  * @since 0.71
@@ -870,6 +949,10 @@
  *
  * @since 2.0.0
  *
+ * @global WP       $wp_locale
+ * @global WP_Query $wp_query
+ * @global WP_Query $wp_the_query
+ *
  * @param string|array $query_vars Default WP_Query arguments.
  */
 function wp( $query_vars = '' ) {
@@ -885,6 +968,8 @@
  *
  * @since 2.3.0
  *
+ * @global array $wp_header_to_desc
+ *
  * @param int $code HTTP status code.
  * @return string Empty string if not found, or description if found.
  */
@@ -917,6 +1002,7 @@
 			305 => 'Use Proxy',
 			306 => 'Reserved',
 			307 => 'Temporary Redirect',
+			308 => 'Permanent Redirect',
 
 			400 => 'Bad Request',
 			401 => 'Unauthorized',
@@ -937,6 +1023,7 @@
 			416 => 'Requested Range Not Satisfiable',
 			417 => 'Expectation Failed',
 			418 => 'I\'m a teapot',
+			421 => 'Misdirected Request',
 			422 => 'Unprocessable Entity',
 			423 => 'Locked',
 			424 => 'Failed Dependency',
@@ -944,6 +1031,7 @@
 			428 => 'Precondition Required',
 			429 => 'Too Many Requests',
 			431 => 'Request Header Fields Too Large',
+			451 => 'Unavailable For Legal Reasons',
 
 			500 => 'Internal Server Error',
 			501 => 'Not Implemented',
@@ -968,25 +1056,28 @@
  * Set HTTP status header.
  *
  * @since 2.0.0
+ * @since 4.4.0 Added the `$description` parameter.
  *
  * @see get_status_header_desc()
  *
- * @param int $code HTTP status code.
- */
-function status_header( $code ) {
-	$description = get_status_header_desc( $code );
-
-	if ( empty( $description ) )
+ * @param int    $code        HTTP status code.
+ * @param string $description Optional. A custom description for the HTTP status.
+ */
+function status_header( $code, $description = '' ) {
+	if ( ! $description ) {
+		$description = get_status_header_desc( $code );
+	}
+
+	if ( empty( $description ) ) {
 		return;
-
-	$protocol = $_SERVER['SERVER_PROTOCOL'];
-	if ( 'HTTP/1.1' != $protocol && 'HTTP/1.0' != $protocol )
-		$protocol = 'HTTP/1.0';
+	}
+
+	$protocol = wp_get_server_protocol();
 	$status_header = "$protocol $code $description";
 	if ( function_exists( 'apply_filters' ) )
 
 		/**
-		 * Filter an HTTP status header.
+		 * Filters an HTTP status header.
 		 *
 		 * @since 2.2.0
 		 *
@@ -1014,12 +1105,11 @@
 	$headers = array(
 		'Expires' => 'Wed, 11 Jan 1984 05:00:00 GMT',
 		'Cache-Control' => 'no-cache, must-revalidate, max-age=0',
-		'Pragma' => 'no-cache',
 	);
 
 	if ( function_exists('apply_filters') ) {
 		/**
-		 * Filter the cache-controlling headers.
+		 * Filters the cache-controlling headers.
 		 *
 		 * @since 2.8.0
 		 *
@@ -1030,7 +1120,6 @@
 		 *
 		 *     @type string $Expires       Expires header.
 		 *     @type string $Cache-Control Cache-Control header.
-		 *     @type string $Pragma        Pragma header.
 		 * }
 		 */
 		$headers = (array) apply_filters( 'nocache_headers', $headers );
@@ -1069,7 +1158,7 @@
 		}
 	}
 
-	foreach( $headers as $name => $field_value )
+	foreach ( $headers as $name => $field_value )
 		@header("{$name}: {$field_value}");
 }
 
@@ -1124,7 +1213,7 @@
  *
  * @since 2.1.0
  *
- * @uses $wp_query Used to tell if the use a comment feed.
+ * @global WP_Query $wp_query Used to tell if the use a comment feed.
  */
 function do_feed() {
 	global $wp_query;
@@ -1137,20 +1226,23 @@
 	if ( $feed == '' || $feed == 'feed' )
 		$feed = get_default_feed();
 
-	$hook = 'do_feed_' . $feed;
-	if ( ! has_action( $hook ) )
+	if ( ! has_action( "do_feed_{$feed}" ) ) {
 		wp_die( __( 'ERROR: This is not a valid feed template.' ), '', array( 'response' => 404 ) );
+	}
 
 	/**
 	 * Fires once the given feed is loaded.
 	 *
-	 * The dynamic hook name, $hook, refers to the feed name.
+	 * The dynamic portion of the hook name, `$feed`, refers to the feed template name.
+	 * Possible values include: 'rdf', 'rss', 'rss2', and 'atom'.
 	 *
 	 * @since 2.1.0
+	 * @since 4.4.0 The `$feed` parameter was added.
 	 *
-	 * @param bool $is_comment_feed Whether the feed is a comment feed.
+	 * @param bool   $is_comment_feed Whether the feed is a comment feed.
+	 * @param string $feed            The feed name.
 	 */
-	do_action( $hook, $wp_query->is_comment_feed );
+	do_action( "do_feed_{$feed}", $wp_query->is_comment_feed, $feed );
 }
 
 /**
@@ -1233,10 +1325,11 @@
 		$site_url = parse_url( site_url() );
 		$path = ( !empty( $site_url['path'] ) ) ? $site_url['path'] : '';
 		$output .= "Disallow: $path/wp-admin/\n";
+		$output .= "Allow: $path/wp-admin/admin-ajax.php\n";
 	}
 
 	/**
-	 * Filter the robots.txt output.
+	 * Filters the robots.txt output.
 	 *
 	 * @since 3.0.0
 	 *
@@ -1247,7 +1340,7 @@
 }
 
 /**
- * Test whether blog is already installed.
+ * Test whether WordPress is already installed.
  *
  * The cache will be checked first. If you have a cache plugin, which saves
  * the cache values, then this will work. If you use the default WordPress
@@ -1259,7 +1352,7 @@
  *
  * @global wpdb $wpdb WordPress database abstraction object.
  *
- * @return bool Whether the blog is already installed.
+ * @return bool Whether the site is already installed.
  */
 function is_blog_installed() {
 	global $wpdb;
@@ -1272,7 +1365,7 @@
 		return true;
 
 	$suppress = $wpdb->suppress_errors();
-	if ( ! defined( 'WP_INSTALLING' ) ) {
+	if ( ! wp_installing() ) {
 		$alloptions = wp_load_alloptions();
 	}
 	// If siteurl is not set to autoload, check it specifically
@@ -1295,13 +1388,13 @@
 	$suppress = $wpdb->suppress_errors();
 
 	/*
-	 * Loop over the WP tables. If none exist, then scratch install is allowed.
+	 * Loop over the WP tables. If none exist, then scratch installation is allowed.
 	 * If one or more exist, suggest table repair since we got here because the
 	 * options table could not be accessed.
 	 */
 	$wp_tables = $wpdb->tables();
 	foreach ( $wp_tables as $table ) {
-		// The existence of custom user tables shouldn't suggest an insane state or prevent a clean install.
+		// The existence of custom user tables shouldn't suggest an insane state or prevent a clean installation.
 		if ( defined( 'CUSTOM_USER_TABLE' ) && CUSTOM_USER_TABLE == $table )
 			continue;
 		if ( defined( 'CUSTOM_USER_META_TABLE' ) && CUSTOM_USER_META_TABLE == $table )
@@ -1315,7 +1408,12 @@
 		wp_load_translations_early();
 
 		// Die with a DB error.
-		$wpdb->error = sprintf( __( 'One or more database tables are unavailable. The database may need to be <a href="%s">repaired</a>.' ), 'maint/repair.php?referrer=is_blog_installed' );
+		$wpdb->error = sprintf(
+			/* translators: %s: database repair URL */
+			__( 'One or more database tables are unavailable. The database may need to be <a href="%s">repaired</a>.' ),
+			'maint/repair.php?referrer=is_blog_installed'
+		);
+
 		dead_db();
 	}
 
@@ -1433,16 +1531,35 @@
  * @return false|string False on failure. Referer URL on success.
  */
 function wp_get_referer() {
-	if ( ! function_exists( 'wp_validate_redirect' ) )
+	if ( ! function_exists( 'wp_validate_redirect' ) ) {
 		return false;
-	$ref = false;
-	if ( ! empty( $_REQUEST['_wp_http_referer'] ) )
-		$ref = wp_unslash( $_REQUEST['_wp_http_referer'] );
-	elseif ( ! empty( $_SERVER['HTTP_REFERER'] ) )
-		$ref = wp_unslash( $_SERVER['HTTP_REFERER'] );
-
-	if ( $ref && $ref !== wp_unslash( $_SERVER['REQUEST_URI'] ) )
+	}
+
+	$ref = wp_get_raw_referer();
+
+	if ( $ref && $ref !== wp_unslash( $_SERVER['REQUEST_URI'] ) && $ref !== home_url() . wp_unslash( $_SERVER['REQUEST_URI'] ) ) {
 		return wp_validate_redirect( $ref, false );
+	}
+
+	return false;
+}
+
+/**
+ * Retrieves unvalidated referer from '_wp_http_referer' or HTTP referer.
+ *
+ * Do not use for redirects, use wp_get_referer() instead.
+ *
+ * @since 4.5.0
+ *
+ * @return string|false Referer URL on success, false on failure.
+ */
+function wp_get_raw_referer() {
+	if ( ! empty( $_REQUEST['_wp_http_referer'] ) ) {
+		return wp_unslash( $_REQUEST['_wp_http_referer'] );
+	} else if ( ! empty( $_SERVER['HTTP_REFERER'] ) ) {
+		return wp_unslash( $_SERVER['HTTP_REFERER'] );
+	}
+
 	return false;
 }
 
@@ -1473,7 +1590,7 @@
 	$wrapper = null;
 
 	// Strip the protocol.
-	if( wp_is_stream( $target ) ) {
+	if ( wp_is_stream( $target ) ) {
 		list( $wrapper, $target ) = explode( '://', $target, 2 );
 	}
 
@@ -1481,7 +1598,7 @@
 	$target = str_replace( '//', '/', $target );
 
 	// Put the wrapper back on the target.
-	if( $wrapper !== null ) {
+	if ( $wrapper !== null ) {
 		$target = $wrapper . '://' . $target;
 	}
 
@@ -1498,7 +1615,7 @@
 
 	// We need to find the permissions of the parent folder that exists and inherit that.
 	$target_parent = dirname( $target );
-	while ( '.' != $target_parent && ! is_dir( $target_parent ) ) {
+	while ( '.' != $target_parent && ! is_dir( $target_parent ) && dirname( $target_parent ) !== $target_parent ) {
 		$target_parent = dirname( $target_parent );
 	}
 
@@ -1529,7 +1646,7 @@
 }
 
 /**
- * Test if a give filesystem path is absolute.
+ * Test if a given filesystem path is absolute.
  *
  * For example, '/foo/bar', or 'c:\windows'.
  *
@@ -1579,18 +1696,38 @@
 /**
  * Normalize a filesystem path.
  *
- * Replaces backslashes with forward slashes for Windows systems, and ensures
- * no duplicate slashes exist.
+ * On windows systems, replaces backslashes with forward slashes
+ * and forces upper-case drive letters.
+ * Allows for two leading slashes for Windows network shares, but
+ * ensures that all other duplicate slashes are reduced to a single.
  *
  * @since 3.9.0
+ * @since 4.4.0 Ensures upper-case drive letters on Windows systems.
+ * @since 4.5.0 Allows for Windows network shares.
+ * @since 4.9.7 Allows for PHP file wrappers.
  *
  * @param string $path Path to normalize.
  * @return string Normalized path.
  */
 function wp_normalize_path( $path ) {
+	$wrapper = '';
+	if ( wp_is_stream( $path ) ) {
+		list( $wrapper, $path ) = explode( '://', $path, 2 );
+		$wrapper .= '://';
+	}
+
+	// Standardise all paths to use /
 	$path = str_replace( '\\', '/', $path );
-	$path = preg_replace( '|/+|','/', $path );
-	return $path;
+
+	// Replace multiple slashes down to a singular, allowing for network shares having two slashes.
+	$path = preg_replace( '|(?<=.)/+|', '/', $path );
+
+	// Windows paths should uppercase the drive letter
+	if ( ':' === substr( $path, 1, 1 ) ) {
+		$path = ucfirst( $path );
+	}
+
+	return $wrapper . $path;
 }
 
 /**
@@ -1605,10 +1742,12 @@
  *
  * @since 2.5.0
  *
+ * @staticvar string $temp
+ *
  * @return string Writable temporary directory.
  */
 function get_temp_dir() {
-	static $temp;
+	static $temp = '';
 	if ( defined('WP_TEMP_DIR') )
 		return trailingslashit(WP_TEMP_DIR);
 
@@ -1629,8 +1768,7 @@
 	if ( is_dir( $temp ) && wp_is_writable( $temp ) )
 		return $temp;
 
-	$temp = '/tmp/';
-	return $temp;
+	return '/tmp/';
 }
 
 /**
@@ -1663,8 +1801,8 @@
  *
  * @since 2.8.0
  *
- * @see http://bugs.php.net/bug.php?id=27609
- * @see http://bugs.php.net/bug.php?id=30931
+ * @see https://bugs.php.net/bug.php?id=27609
+ * @see https://bugs.php.net/bug.php?id=30931
  *
  * @param string $path Windows path to check for write-ability.
  * @return bool Whether the path is writable.
@@ -1688,6 +1826,23 @@
 }
 
 /**
+ * Retrieves uploads directory information.
+ *
+ * Same as wp_upload_dir() but "light weight" as it doesn't attempt to create the uploads directory.
+ * Intended for use in themes, when only 'basedir' and 'baseurl' are needed, generally in all cases
+ * when not uploading files.
+ *
+ * @since 4.5.0
+ *
+ * @see wp_upload_dir()
+ *
+ * @return array See wp_upload_dir() for description.
+ */
+function wp_get_upload_dir() {
+	return wp_upload_dir( null, false );
+}
+
+/**
  * Get an array containing the current upload directory's path and url.
  *
  * Checks the 'upload_path' option, which should be from the web root folder,
@@ -1712,14 +1867,76 @@
  * 'subdir' - sub directory if uploads use year/month folders option is on.
  * 'basedir' - path without subdir.
  * 'baseurl' - URL path without subdir.
- * 'error' - set to false.
+ * 'error' - false or error message.
  *
  * @since 2.0.0
+ * @uses _wp_upload_dir()
+ *
+ * @staticvar array $cache
+ * @staticvar array $tested_paths
  *
  * @param string $time Optional. Time formatted in 'yyyy/mm'. Default null.
+ * @param bool   $create_dir Optional. Whether to check and create the uploads directory.
+ *                           Default true for backward compatibility.
+ * @param bool   $refresh_cache Optional. Whether to refresh the cache. Default false.
  * @return array See above for description.
  */
-function wp_upload_dir( $time = null ) {
+function wp_upload_dir( $time = null, $create_dir = true, $refresh_cache = false ) {
+	static $cache = array(), $tested_paths = array();
+
+	$key = sprintf( '%d-%s', get_current_blog_id(), (string) $time );
+
+	if ( $refresh_cache || empty( $cache[ $key ] ) ) {
+		$cache[ $key ] = _wp_upload_dir( $time );
+	}
+
+	/**
+	 * Filters the uploads directory data.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $uploads Array of upload directory data with keys of 'path',
+	 *                       'url', 'subdir, 'basedir', and 'error'.
+	 */
+	$uploads = apply_filters( 'upload_dir', $cache[ $key ] );
+
+	if ( $create_dir ) {
+		$path = $uploads['path'];
+
+		if ( array_key_exists( $path, $tested_paths ) ) {
+			$uploads['error'] = $tested_paths[ $path ];
+		} else {
+			if ( ! wp_mkdir_p( $path ) ) {
+				if ( 0 === strpos( $uploads['basedir'], ABSPATH ) ) {
+					$error_path = str_replace( ABSPATH, '', $uploads['basedir'] ) . $uploads['subdir'];
+				} else {
+					$error_path = basename( $uploads['basedir'] ) . $uploads['subdir'];
+				}
+
+				$uploads['error'] = sprintf(
+					/* translators: %s: directory path */
+					__( 'Unable to create directory %s. Is its parent directory writable by the server?' ),
+					esc_html( $error_path )
+				);
+			}
+
+			$tested_paths[ $path ] = $uploads['error'];
+		}
+	}
+
+	return $uploads;
+}
+
+/**
+ * A non-filtered, non-cached version of wp_upload_dir() that doesn't check the path.
+ *
+ * @since 4.5.0
+ * @access private
+ *
+ * @param string $time Optional. Time formatted in 'yyyy/mm'. Default null.
+ * @return array See wp_upload_dir()
+ */
+function _wp_upload_dir( $time = null ) {
 	$siteurl = get_option( 'siteurl' );
 	$upload_path = trim( get_option( 'upload_path' ) );
 
@@ -1808,36 +2025,14 @@
 	$dir .= $subdir;
 	$url .= $subdir;
 
-	/**
-	 * Filter the uploads directory data.
-	 *
-	 * @since 2.0.0
-	 *
-	 * @param array $uploads Array of upload directory data with keys of 'path',
-	 *                       'url', 'subdir, 'basedir', and 'error'.
-	 */
-	$uploads = apply_filters( 'upload_dir',
-		array(
-			'path'    => $dir,
-			'url'     => $url,
-			'subdir'  => $subdir,
-			'basedir' => $basedir,
-			'baseurl' => $baseurl,
-			'error'   => false,
-		) );
-
-	// Make sure we have an uploads directory.
-	if ( ! wp_mkdir_p( $uploads['path'] ) ) {
-		if ( 0 === strpos( $uploads['basedir'], ABSPATH ) )
-			$error_path = str_replace( ABSPATH, '', $uploads['basedir'] ) . $uploads['subdir'];
-		else
-			$error_path = basename( $uploads['basedir'] ) . $uploads['subdir'];
-
-		$message = sprintf( __( 'Unable to create directory %s. Is its parent directory writable by the server?' ), $error_path );
-		$uploads['error'] = $message;
-	}
-
-	return $uploads;
+	return array(
+		'path'    => $dir,
+		'url'     => $url,
+		'subdir'  => $subdir,
+		'basedir' => $basedir,
+		'baseurl' => $baseurl,
+		'error'   => false,
+	);
 }
 
 /**
@@ -1854,7 +2049,7 @@
  *
  * @param string   $dir                      Directory.
  * @param string   $filename                 File name.
- * @param callback $unique_filename_callback Callback. Default null.
+ * @param callable $unique_filename_callback Callback. Default null.
  * @return string New filename, if given wasn't unique.
  */
 function wp_unique_filename( $dir, $filename, $unique_filename_callback = null ) {
@@ -1862,13 +2057,16 @@
 	$filename = sanitize_file_name($filename);
 
 	// Separate the filename into a name and extension.
-	$info = pathinfo($filename);
-	$ext = !empty($info['extension']) ? '.' . $info['extension'] : '';
-	$name = basename($filename, $ext);
+	$ext = pathinfo( $filename, PATHINFO_EXTENSION );
+	$name = pathinfo( $filename, PATHINFO_BASENAME );
+	if ( $ext ) {
+		$ext = '.' . $ext;
+	}
 
 	// Edge case: if file is named '.ext', treat as an empty name.
-	if ( $name === $ext )
+	if ( $name === $ext ) {
 		$name = '';
+	}
 
 	/*
 	 * Increment the file number until we have a unique file to save in $dir.
@@ -1886,23 +2084,38 @@
 
 			// Check for both lower and upper case extension or image sub-sizes may be overwritten.
 			while ( file_exists($dir . "/$filename") || file_exists($dir . "/$filename2") ) {
-				$new_number = $number + 1;
-				$filename = str_replace( "$number$ext", "$new_number$ext", $filename );
-				$filename2 = str_replace( "$number$ext2", "$new_number$ext2", $filename2 );
+				$new_number = (int) $number + 1;
+				$filename = str_replace( array( "-$number$ext", "$number$ext" ), "-$new_number$ext", $filename );
+				$filename2 = str_replace( array( "-$number$ext2", "$number$ext2" ), "-$new_number$ext2", $filename2 );
 				$number = $new_number;
 			}
-			return $filename2;
+
+			/**
+			 * Filters the result when generating a unique file name.
+			 *
+			 * @since 4.5.0
+			 *
+			 * @param string        $filename                 Unique file name.
+			 * @param string        $ext                      File extension, eg. ".png".
+			 * @param string        $dir                      Directory path.
+			 * @param callable|null $unique_filename_callback Callback function that generates the unique file name.
+			 */
+			return apply_filters( 'wp_unique_filename', $filename2, $ext, $dir, $unique_filename_callback );
 		}
 
 		while ( file_exists( $dir . "/$filename" ) ) {
-			if ( '' == "$number$ext" )
-				$filename = $filename . ++$number . $ext;
-			else
-				$filename = str_replace( "$number$ext", ++$number . $ext, $filename );
+			$new_number = (int) $number + 1;
+			if ( '' == "$number$ext" ) {
+				$filename = "$filename-" . $new_number;
+			} else {
+				$filename = str_replace( array( "-$number$ext", "$number$ext" ), "-" . $new_number . $ext, $filename );
+			}
+			$number = $new_number;
 		}
 	}
 
-	return $filename;
+	/** This filter is documented in wp-includes/functions.php */
+	return apply_filters( 'wp_unique_filename', $filename, $ext, $dir, $unique_filename_callback );
 }
 
 /**
@@ -1930,14 +2143,14 @@
  */
 function wp_upload_bits( $name, $deprecated, $bits, $time = null ) {
 	if ( !empty( $deprecated ) )
-		_deprecated_argument( __FUNCTION__, '2.0' );
+		_deprecated_argument( __FUNCTION__, '2.0.0' );
 
 	if ( empty( $name ) )
 		return array( 'error' => __( 'Empty filename' ) );
 
 	$wp_filetype = wp_check_filetype( $name );
 	if ( ! $wp_filetype['ext'] && ! current_user_can( 'unfiltered_upload' ) )
-		return array( 'error' => __( 'Invalid file type' ) );
+		return array( 'error' => __( 'Sorry, this file type is not permitted for security reasons.' ) );
 
 	$upload = wp_upload_dir( $time );
 
@@ -1945,7 +2158,7 @@
 		return $upload;
 
 	/**
-	 * Filter whether to treat the upload bits as an error.
+	 * Filters whether to treat the upload bits as an error.
 	 *
 	 * Passing a non-array to the filter will effectively short-circuit preparing
 	 * the upload bits, returning that value instead.
@@ -1969,7 +2182,11 @@
 		else
 			$error_path = basename( $upload['basedir'] ) . $upload['subdir'];
 
-		$message = sprintf( __( 'Unable to create directory %s. Is its parent directory writable by the server?' ), $error_path );
+		$message = sprintf(
+			/* translators: %s: directory path */
+			__( 'Unable to create directory %s. Is its parent directory writable by the server?' ),
+			$error_path
+		);
 		return array( 'error' => $message );
 	}
 
@@ -1991,7 +2208,8 @@
 	// Compute the URL
 	$url = $upload['url'] . "/$filename";
 
-	return array( 'file' => $new_file, 'url' => $url, 'error' => false );
+	/** This filter is documented in wp-admin/includes/file.php */
+	return apply_filters( 'wp_handle_upload', array( 'file' => $new_file, 'url' => $url, 'type' => $wp_filetype['type'], 'error' => false ), 'sideload' );
 }
 
 /**
@@ -2000,39 +2218,15 @@
  * @since 2.5.0
  *
  * @param string $ext The extension to search.
- * @return string|null The file type, example: audio, video, document, spreadsheet, etc.
- *                     Null if not found.
+ * @return string|void The file type, example: audio, video, document, spreadsheet, etc.
  */
 function wp_ext2type( $ext ) {
 	$ext = strtolower( $ext );
 
-	/**
-	 * Filter file type based on the extension name.
-	 *
-	 * @since 2.5.0
-	 *
-	 * @see wp_ext2type()
-	 *
-	 * @param array $ext2type Multi-dimensional array with extensions for a default set
-	 *                        of file types.
-	 */
-	$ext2type = apply_filters( 'ext2type', array(
-		'image'       => array( 'jpg', 'jpeg', 'jpe',  'gif',  'png',  'bmp',   'tif',  'tiff', 'ico' ),
-		'audio'       => array( 'aac', 'ac3',  'aif',  'aiff', 'm3a',  'm4a',   'm4b',  'mka',  'mp1',  'mp2',  'mp3', 'ogg', 'oga', 'ram', 'wav', 'wma' ),
-		'video'       => array( '3g2',  '3gp', '3gpp', 'asf', 'avi',  'divx', 'dv',   'flv',  'm4v',   'mkv',  'mov',  'mp4',  'mpeg', 'mpg', 'mpv', 'ogm', 'ogv', 'qt',  'rm', 'vob', 'wmv' ),
-		'document'    => array( 'doc', 'docx', 'docm', 'dotm', 'odt',  'pages', 'pdf',  'xps',  'oxps', 'rtf',  'wp', 'wpd', 'psd', 'xcf' ),
-		'spreadsheet' => array( 'numbers',     'ods',  'xls',  'xlsx', 'xlsm',  'xlsb' ),
-		'interactive' => array( 'swf', 'key',  'ppt',  'pptx', 'pptm', 'pps',   'ppsx', 'ppsm', 'sldx', 'sldm', 'odp' ),
-		'text'        => array( 'asc', 'csv',  'tsv',  'txt' ),
-		'archive'     => array( 'bz2', 'cab',  'dmg',  'gz',   'rar',  'sea',   'sit',  'sqx',  'tar',  'tgz',  'zip', '7z' ),
-		'code'        => array( 'css', 'htm',  'html', 'php',  'js' ),
-	) );
-
+	$ext2type = wp_get_ext_types();
 	foreach ( $ext2type as $type => $exts )
 		if ( in_array( $ext, $exts ) )
 			return $type;
-
-	return null;
 }
 
 /**
@@ -2072,7 +2266,7 @@
  * If it's determined that the extension does not match the file's real type,
  * then the "proper_filename" value will be set with a proper filename and extension.
  *
- * Currently this function only supports validating images known to getimagesize().
+ * Currently this function only supports renaming images validated via wp_get_image_mime().
  *
  * @since 3.0.0
  *
@@ -2084,7 +2278,6 @@
  *               if original $filename is valid.
  */
 function wp_check_filetype_and_ext( $file, $filename, $mimes = null ) {
-
 	$proper_filename = false;
 
 	// Do basic extension validation and MIME mapping
@@ -2097,16 +2290,17 @@
 		return compact( 'ext', 'type', 'proper_filename' );
 	}
 
-	// We're able to validate images using GD
-	if ( $type && 0 === strpos( $type, 'image/' ) && function_exists('getimagesize') ) {
+	$real_mime = false;
+
+	// Validate image types.
+	if ( $type && 0 === strpos( $type, 'image/' ) ) {
 
 		// Attempt to figure out what type of image it actually is
-		$imgstats = @getimagesize( $file );
-
-		// If getimagesize() knows what kind of image it really is and if the real MIME doesn't match the claimed MIME
-		if ( !empty($imgstats['mime']) && $imgstats['mime'] != $type ) {
+		$real_mime = wp_get_image_mime( $file );
+
+		if ( $real_mime && $real_mime != $type ) {
 			/**
-			 * Filter the list mapping image mime types to their respective extensions.
+			 * Filters the list mapping image mime types to their respective extensions.
 			 *
 			 * @since 3.0.0
 			 *
@@ -2121,10 +2315,10 @@
 			) );
 
 			// Replace whatever is after the last period in the filename with the correct extension
-			if ( ! empty( $mime_to_ext[ $imgstats['mime'] ] ) ) {
+			if ( ! empty( $mime_to_ext[ $real_mime ] ) ) {
 				$filename_parts = explode( '.', $filename );
 				array_pop( $filename_parts );
-				$filename_parts[] = $mime_to_ext[ $imgstats['mime'] ];
+				$filename_parts[] = $mime_to_ext[ $real_mime ];
 				$new_filename = implode( '.', $filename_parts );
 
 				if ( $new_filename != $filename ) {
@@ -2134,12 +2328,35 @@
 				$wp_filetype = wp_check_filetype( $new_filename, $mimes );
 				$ext = $wp_filetype['ext'];
 				$type = $wp_filetype['type'];
+			} else {
+				// Reset $real_mime and try validating again.
+				$real_mime = false;
+			}
+		}
+	}
+
+	// Validate files that didn't get validated during previous checks.
+	if ( $type && ! $real_mime && extension_loaded( 'fileinfo' ) ) {
+		$finfo = finfo_open( FILEINFO_MIME_TYPE );
+		$real_mime = finfo_file( $finfo, $file );
+		finfo_close( $finfo );
+
+		/*
+		 * If $real_mime doesn't match what we're expecting, we need to do some extra
+		 * vetting of application mime types to make sure this type of file is allowed.
+		 * Other mime types are assumed to be safe, but should be considered unverified.
+		 */
+		if ( $real_mime && ( $real_mime !== $type ) && ( 0 === strpos( $real_mime, 'application' ) ) ) {
+			$allowed = get_allowed_mime_types();
+
+			if ( ! in_array( $real_mime, $allowed ) ) {
+				$type = $ext = false;
 			}
 		}
 	}
 
 	/**
-	 * Filter the "real" file type of the given file.
+	 * Filters the "real" file type of the given file.
 	 *
 	 * @since 3.0.0
 	 *
@@ -2154,6 +2371,39 @@
 }
 
 /**
+ * Returns the real mime type of an image file.
+ *
+ * This depends on exif_imagetype() or getimagesize() to determine real mime types.
+ *
+ * @since 4.7.1
+ *
+ * @param string $file Full path to the file.
+ * @return string|false The actual mime type or false if the type cannot be determined.
+ */
+function wp_get_image_mime( $file ) {
+	/*
+	 * Use exif_imagetype() to check the mimetype if available or fall back to
+	 * getimagesize() if exif isn't avaialbe. If either function throws an Exception
+	 * we assume the file could not be validated.
+	 */
+	try {
+		if ( is_callable( 'exif_imagetype' ) ) {
+			$imagetype = exif_imagetype( $file );
+			$mime = ( $imagetype ) ? image_type_to_mime_type( $imagetype ) : false;
+		} elseif ( function_exists( 'getimagesize' ) ) {
+			$imagesize = getimagesize( $file );
+			$mime = ( isset( $imagesize['mime'] ) ) ? $imagesize['mime'] : false;
+		} else {
+			$mime = false;
+		}
+	} catch ( Exception $e ) {
+		$mime = false;
+	}
+
+	return $mime;
+}
+
+/**
  * Retrieve list of mime types and file extensions.
  *
  * @since 3.5.0
@@ -2163,10 +2413,10 @@
  */
 function wp_get_mime_types() {
 	/**
-	 * Filter the list of mime types and file extensions.
+	 * Filters the list of mime types and file extensions.
 	 *
 	 * This filter should be used to add, not remove, mime types. To remove
-	 * mime types, use the 'upload_mimes' filter.
+	 * mime types, use the {@see 'upload_mimes'} filter.
 	 *
 	 * @since 3.5.0
 	 *
@@ -2209,9 +2459,11 @@
 	'dfxp' => 'application/ttaf+xml',
 	// Audio formats.
 	'mp3|m4a|m4b' => 'audio/mpeg',
+	'aac' => 'audio/aac',
 	'ra|ram' => 'audio/x-realaudio',
 	'wav' => 'audio/wav',
 	'ogg|oga' => 'audio/ogg',
+	'flac' => 'audio/flac',
 	'mid|midi' => 'audio/midi',
 	'wma' => 'audio/x-ms-wma',
 	'wax' => 'audio/x-ms-wax',
@@ -2275,6 +2527,39 @@
 	'pages' => 'application/vnd.apple.pages',
 	) );
 }
+
+/**
+ * Retrieves the list of common file extensions and their types.
+ *
+ * @since 4.6.0
+ *
+ * @return array Array of file extensions types keyed by the type of file.
+ */
+function wp_get_ext_types() {
+
+	/**
+	 * Filters file type based on the extension name.
+	 *
+	 * @since 2.5.0
+	 *
+	 * @see wp_ext2type()
+	 *
+	 * @param array $ext2type Multi-dimensional array with extensions for a default set
+	 *                        of file types.
+	 */
+	return apply_filters( 'ext2type', array(
+		'image'       => array( 'jpg', 'jpeg', 'jpe',  'gif',  'png',  'bmp',   'tif',  'tiff', 'ico' ),
+		'audio'       => array( 'aac', 'ac3',  'aif',  'aiff', 'flac', 'm3a',  'm4a',   'm4b',  'mka',  'mp1',  'mp2',  'mp3', 'ogg', 'oga', 'ram', 'wav', 'wma' ),
+		'video'       => array( '3g2',  '3gp', '3gpp', 'asf', 'avi',  'divx', 'dv',   'flv',  'm4v',   'mkv',  'mov',  'mp4',  'mpeg', 'mpg', 'mpv', 'ogm', 'ogv', 'qt',  'rm', 'vob', 'wmv' ),
+		'document'    => array( 'doc', 'docx', 'docm', 'dotm', 'odt',  'pages', 'pdf',  'xps',  'oxps', 'rtf',  'wp', 'wpd', 'psd', 'xcf' ),
+		'spreadsheet' => array( 'numbers',     'ods',  'xls',  'xlsx', 'xlsm',  'xlsb' ),
+		'interactive' => array( 'swf', 'key',  'ppt',  'pptx', 'pptm', 'pps',   'ppsx', 'ppsm', 'sldx', 'sldm', 'odp' ),
+		'text'        => array( 'asc', 'csv',  'tsv',  'txt' ),
+		'archive'     => array( 'bz2', 'cab',  'dmg',  'gz',   'rar',  'sea',   'sit',  'sqx',  'tar',  'tgz',  'zip', '7z' ),
+		'code'        => array( 'css', 'htm',  'html', 'php',  'js' ),
+	) );
+}
+
 /**
  * Retrieve list of allowed mime types and file extensions.
  *
@@ -2291,11 +2576,12 @@
 	if ( function_exists( 'current_user_can' ) )
 		$unfiltered = $user ? user_can( $user, 'unfiltered_html' ) : current_user_can( 'unfiltered_html' );
 
-	if ( empty( $unfiltered ) )
-		unset( $t['htm|html'] );
+	if ( empty( $unfiltered ) ) {
+		unset( $t['htm|html'], $t['js'] );
+	}
 
 	/**
-	 * Filter list of allowed mime types and file extensions.
+	 * Filters list of allowed mime types and file extensions.
 	 *
 	 * @since 2.0.0
 	 *
@@ -2319,16 +2605,30 @@
  */
 function wp_nonce_ays( $action ) {
 	if ( 'log-out' == $action ) {
-		$html = sprintf( __( 'You are attempting to log out of %s' ), get_bloginfo( 'name' ) ) . '</p><p>';
+		$html = sprintf(
+			/* translators: %s: site name */
+			__( 'You are attempting to log out of %s' ),
+			get_bloginfo( 'name' )
+		);
+		$html .= '</p><p>';
 		$redirect_to = isset( $_REQUEST['redirect_to'] ) ? $_REQUEST['redirect_to'] : '';
-		$html .= sprintf( __( "Do you really want to <a href='%s'>log out</a>?"), wp_logout_url( $redirect_to ) );
+		$html .= sprintf(
+			/* translators: %s: logout URL */
+			__( 'Do you really want to <a href="%s">log out</a>?' ),
+			wp_logout_url( $redirect_to )
+		);
 	} else {
-		$html = __( 'Are you sure you want to do this?' );
-		if ( wp_get_referer() )
-			$html .= "</p><p><a href='" . esc_url( remove_query_arg( 'updated', wp_get_referer() ) ) . "'>" . __( 'Please try again.' ) . "</a>";
-	}
-
-	wp_die( $html, __( 'WordPress Failure Notice' ), 403 );
+		$html = __( 'The link you followed has expired.' );
+		if ( wp_get_referer() ) {
+			$html .= '</p><p>';
+			$html .= sprintf( '<a href="%s">%s</a>',
+				esc_url( remove_query_arg( 'updated', wp_get_referer() ) ),
+				__( 'Please try again.' )
+			);
+		}
+	}
+
+	wp_die( $html, __( 'Something went wrong.' ), 403 );
 }
 
 /**
@@ -2347,8 +2647,9 @@
  * @since 4.1.0 The `$title` and `$args` parameters were changed to optionally accept
  *              an integer to be used as the response code.
  *
- * @param string|WP_Error  $message Optional. Error message. If this is a {@see WP_Error} object,
- *                                  the error's messages are used. Default empty.
+ * @param string|WP_Error  $message Optional. Error message. If this is a WP_Error object,
+ *                                  and not an Ajax or XML-RPC request, the error's messages are used.
+ *                                  Default empty.
  * @param string|int       $title   Optional. Error title. If `$message` is a `WP_Error` object,
  *                                  error data with the key 'title' may be used to specify the title.
  *                                  If `$title` is an integer, then it is treated as the response
@@ -2357,11 +2658,11 @@
  *     Optional. Arguments to control behavior. If `$args` is an integer, then it is treated
  *     as the response code. Default empty array.
  *
- *     @type int    $response       The HTTP response code. Default 500.
+ *     @type int    $response       The HTTP response code. Default 200 for Ajax requests, 500 otherwise.
  *     @type bool   $back_link      Whether to include a link to go back. Default false.
  *     @type string $text_direction The text direction. This is only useful internally, when WordPress
  *                                  is still loading and the site's locale is not set up yet. Accepts 'rtl'.
- *                                  Default is the value of {@see is_rtl()}.
+ *                                  Default is the value of is_rtl().
  * }
  */
 function wp_die( $message = '', $title = '', $args = array() ) {
@@ -2373,31 +2674,31 @@
 		$title = '';
 	}
 
-	if ( defined( 'DOING_AJAX' ) && DOING_AJAX ) {
+	if ( wp_doing_ajax() ) {
 		/**
-		 * Filter callback for killing WordPress execution for AJAX requests.
+		 * Filters the callback for killing WordPress execution for Ajax requests.
 		 *
 		 * @since 3.4.0
 		 *
-		 * @param callback $function Callback function name.
+		 * @param callable $function Callback function name.
 		 */
 		$function = apply_filters( 'wp_die_ajax_handler', '_ajax_wp_die_handler' );
 	} elseif ( defined( 'XMLRPC_REQUEST' ) && XMLRPC_REQUEST ) {
 		/**
-		 * Filter callback for killing WordPress execution for XML-RPC requests.
+		 * Filters the callback for killing WordPress execution for XML-RPC requests.
 		 *
 		 * @since 3.4.0
 		 *
-		 * @param callback $function Callback function name.
+		 * @param callable $function Callback function name.
 		 */
 		$function = apply_filters( 'wp_die_xmlrpc_handler', '_xmlrpc_wp_die_handler' );
 	} else {
 		/**
-		 * Filter callback for killing WordPress execution for all non-AJAX, non-XML-RPC requests.
+		 * Filters the callback for killing WordPress execution for all non-Ajax, non-XML-RPC requests.
 		 *
 		 * @since 3.0.0
 		 *
-		 * @param callback $function Callback function name.
+		 * @param callable $function Callback function name.
 		 */
 		$function = apply_filters( 'wp_die_handler', '_default_wp_die_handler' );
 	}
@@ -2406,17 +2707,17 @@
 }
 
 /**
- * Kill WordPress execution and display HTML message with error message.
+ * Kills WordPress execution and display HTML message with error message.
  *
  * This is the default handler for wp_die if you want a custom one for your
- * site then you can overload using the wp_die_handler filter in wp_die
+ * site then you can overload using the {@see 'wp_die_handler'} filter in wp_die().
  *
  * @since 3.0.0
  * @access private
  *
- * @param string       $message Error message.
- * @param string       $title   Optional. Error title. Default empty.
- * @param string|array $args    Optional. Arguments to control behavior. Default empty array.
+ * @param string|WP_Error $message Error message or WP_Error object.
+ * @param string          $title   Optional. Error title. Default empty.
+ * @param string|array    $args    Optional. Arguments to control behavior. Default empty array.
  */
 function _default_wp_die_handler( $message, $title = '', $args = array() ) {
 	$defaults = array( 'response' => 500 );
@@ -2468,11 +2769,15 @@
 			$text_direction = 'rtl';
 ?>
 <!DOCTYPE html>
-<!-- Ticket #11289, IE bug fix: always pad the error page with enough characters such that it is greater than 512 bytes, even after gzip compression abcdefghijklmnopqrstuvwxyz1234567890aabbccddeeffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz11223344556677889900abacbcbdcdcededfefegfgfhghgihihjijikjkjlklkmlmlnmnmononpopoqpqprqrqsrsrtstsubcbcdcdedefefgfabcadefbghicjkldmnoepqrfstugvwxhyz1i234j567k890laabmbccnddeoeffpgghqhiirjjksklltmmnunoovppqwqrrxsstytuuzvvw0wxx1yyz2z113223434455666777889890091abc2def3ghi4jkl5mno6pqr7stu8vwx9yz11aab2bcc3dd4ee5ff6gg7hh8ii9j0jk1kl2lmm3nnoo4p5pq6qrr7ss8tt9uuvv0wwx1x2yyzz13aba4cbcb5dcdc6dedfef8egf9gfh0ghg1ihi2hji3jik4jkj5lkl6kml7mln8mnm9ono
--->
 <html xmlns="http://www.w3.org/1999/xhtml" <?php if ( function_exists( 'language_attributes' ) && function_exists( 'is_rtl' ) ) language_attributes(); else echo "dir='$text_direction'"; ?>>
 <head>
 	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+	<meta name="viewport" content="width=device-width">
+	<?php
+	if ( function_exists( 'wp_no_robots' ) ) {
+		wp_no_robots();
+	}
+	?>
 	<title><?php echo $title ?></title>
 	<style type="text/css">
 		html {
@@ -2481,7 +2786,7 @@
 		body {
 			background: #fff;
 			color: #444;
-			font-family: "Open Sans", sans-serif;
+			font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
 			margin: 2em auto;
 			padding: 1em 2em;
 			max-width: 700px;
@@ -2492,7 +2797,7 @@
 			border-bottom: 1px solid #dadada;
 			clear: both;
 			color: #666;
-			font: 24px "Open Sans", sans-serif;
+			font-size: 24px;
 			margin: 30px 0 0 0;
 			padding: 0;
 			padding-bottom: 7px;
@@ -2513,15 +2818,25 @@
 			font-size: 14px ;
 		}
 		a {
-			color: #21759B;
-			text-decoration: none;
+			color: #0073aa;
+		}
+		a:hover,
+		a:active {
+			color: #00a0d2;
 		}
-		a:hover {
-			color: #D54E21;
+		a:focus {
+			color: #124964;
+		    -webkit-box-shadow:
+		    	0 0 0 1px #5b9dd9,
+				0 0 2px 1px rgba(30, 140, 190, .8);
+		    box-shadow:
+		    	0 0 0 1px #5b9dd9,
+				0 0 2px 1px rgba(30, 140, 190, .8);
+			outline: none;
 		}
 		.button {
 			background: #f7f7f7;
-			border: 1px solid #cccccc;
+			border: 1px solid #ccc;
 			color: #555;
 			display: inline-block;
 			text-decoration: none;
@@ -2539,40 +2854,46 @@
 			-moz-box-sizing:    border-box;
 			box-sizing:         border-box;
 
-			-webkit-box-shadow: inset 0 1px 0 #fff, 0 1px 0 rgba(0,0,0,.08);
-			box-shadow: inset 0 1px 0 #fff, 0 1px 0 rgba(0,0,0,.08);
+			-webkit-box-shadow: 0 1px 0 #ccc;
+			box-shadow: 0 1px 0 #ccc;
 		 	vertical-align: top;
 		}
 
 		.button.button-large {
-			height: 29px;
+			height: 30px;
 			line-height: 28px;
-			padding: 0 12px;
+			padding: 0 12px 2px;
 		}
 
 		.button:hover,
 		.button:focus {
 			background: #fafafa;
 			border-color: #999;
-			color: #222;
+			color: #23282d;
 		}
 
 		.button:focus  {
-			-webkit-box-shadow: 1px 1px 1px rgba(0,0,0,.2);
-			box-shadow: 1px 1px 1px rgba(0,0,0,.2);
+			border-color: #5b9dd9;
+			-webkit-box-shadow: 0 0 3px rgba( 0, 115, 170, .8 );
+			box-shadow: 0 0 3px rgba( 0, 115, 170, .8 );
+			outline: none;
 		}
 
 		.button:active {
 			background: #eee;
 			border-color: #999;
-			color: #333;
-			-webkit-box-shadow: inset 0 2px 5px -3px rgba( 0, 0, 0, 0.5 );
+		 	-webkit-box-shadow: inset 0 2px 5px -3px rgba( 0, 0, 0, 0.5 );
 		 	box-shadow: inset 0 2px 5px -3px rgba( 0, 0, 0, 0.5 );
+		 	-webkit-transform: translateY(1px);
+		 	-ms-transform: translateY(1px);
+		 	transform: translateY(1px);
 		}
 
-		<?php if ( 'rtl' == $text_direction ) : ?>
-		body { font-family: Tahoma, Arial; }
-		<?php endif; ?>
+		<?php
+		if ( 'rtl' == $text_direction ) {
+			echo 'body { font-family: Tahoma, Arial; }';
+		}
+		?>
 	</style>
 </head>
 <body id="error-page">
@@ -2592,6 +2913,8 @@
  * @since 3.2.0
  * @access private
  *
+ * @global wp_xmlrpc_server $wp_xmlrpc_server
+ *
  * @param string       $message Error message.
  * @param string       $title   Optional. Error title. Default empty.
  * @param string|array $args    Optional. Arguments to control behavior. Default empty array.
@@ -2617,9 +2940,20 @@
  * @since 3.4.0
  * @access private
  *
- * @param string $message Optional. Response to print. Default empty.
- */
-function _ajax_wp_die_handler( $message = '' ) {
+ * @param string       $message Error message.
+ * @param string       $title   Optional. Error title (unused). Default empty.
+ * @param string|array $args    Optional. Arguments to control behavior. Default empty array.
+ */
+function _ajax_wp_die_handler( $message, $title = '', $args = array() ) {
+	$defaults = array(
+		'response' => 200,
+	);
+	$r = wp_parse_args( $args, $defaults );
+
+	if ( ! headers_sent() && null !== $r['response'] ) {
+		status_header( $r['response'] );
+	}
+
 	if ( is_scalar( $message ) )
 		die( (string) $message );
 	die( '0' );
@@ -2650,7 +2984,7 @@
  * @param int   $options Optional. Options to be passed to json_encode(). Default 0.
  * @param int   $depth   Optional. Maximum depth to walk through $data. Must be
  *                       greater than 0. Default 512.
- * @return bool|string The JSON encoded string, or false if it cannot be encoded.
+ * @return string|false The JSON encoded string, or false if it cannot be encoded.
  */
 function wp_json_encode( $data, $options = 0, $depth = 512 ) {
 	/*
@@ -2666,7 +3000,10 @@
 		$args = array( $data );
 	}
 
-	$json = call_user_func_array( 'json_encode', $args );
+	// Prepare the data for JSON serialization.
+	$args[0] = _wp_json_prepare_data( $data );
+
+	$json = @call_user_func_array( 'json_encode', $args );
 
 	// If json_encode() was successful, no need to do more sanity checking.
 	// ... unless we're in an old version of PHP, and json_encode() returned
@@ -2756,6 +3093,8 @@
  *
  * @see _wp_json_sanity_check()
  *
+ * @staticvar bool $use_mb
+ *
  * @param string $string The string which is to be converted.
  * @return string The checked string.
  */
@@ -2778,53 +3117,115 @@
 }
 
 /**
+ * Prepares response data to be serialized to JSON.
+ *
+ * This supports the JsonSerializable interface for PHP 5.2-5.3 as well.
+ *
+ * @ignore
+ * @since 4.4.0
+ * @access private
+ *
+ * @param mixed $data Native representation.
+ * @return bool|int|float|null|string|array Data ready for `json_encode()`.
+ */
+function _wp_json_prepare_data( $data ) {
+	if ( ! defined( 'WP_JSON_SERIALIZE_COMPATIBLE' ) || WP_JSON_SERIALIZE_COMPATIBLE === false ) {
+		return $data;
+	}
+
+	switch ( gettype( $data ) ) {
+		case 'boolean':
+		case 'integer':
+		case 'double':
+		case 'string':
+		case 'NULL':
+			// These values can be passed through.
+			return $data;
+
+		case 'array':
+			// Arrays must be mapped in case they also return objects.
+			return array_map( '_wp_json_prepare_data', $data );
+
+		case 'object':
+			// If this is an incomplete object (__PHP_Incomplete_Class), bail.
+			if ( ! is_object( $data ) ) {
+				return null;
+			}
+
+			if ( $data instanceof JsonSerializable ) {
+				$data = $data->jsonSerialize();
+			} else {
+				$data = get_object_vars( $data );
+			}
+
+			// Now, pass the array (or whatever was returned from jsonSerialize through).
+			return _wp_json_prepare_data( $data );
+
+		default:
+			return null;
+	}
+}
+
+/**
  * Send a JSON response back to an Ajax request.
  *
  * @since 3.5.0
- *
- * @param mixed $response Variable (usually an array or object) to encode as JSON,
- *                        then print and die.
- */
-function wp_send_json( $response ) {
+ * @since 4.7.0 The `$status_code` parameter was added.
+ *
+ * @param mixed $response    Variable (usually an array or object) to encode as JSON,
+ *                           then print and die.
+ * @param int   $status_code The HTTP status code to output.
+ */
+function wp_send_json( $response, $status_code = null ) {
 	@header( 'Content-Type: application/json; charset=' . get_option( 'blog_charset' ) );
+	if ( null !== $status_code ) {
+		status_header( $status_code );
+	}
 	echo wp_json_encode( $response );
-	if ( defined( 'DOING_AJAX' ) && DOING_AJAX )
-		wp_die();
-	else
+
+	if ( wp_doing_ajax() ) {
+		wp_die( '', '', array(
+			'response' => null,
+		) );
+	} else {
 		die;
+	}
 }
 
 /**
  * Send a JSON response back to an Ajax request, indicating success.
  *
  * @since 3.5.0
- *
- * @param mixed $data Data to encode as JSON, then print and die.
- */
-function wp_send_json_success( $data = null ) {
+ * @since 4.7.0 The `$status_code` parameter was added.
+ *
+ * @param mixed $data        Data to encode as JSON, then print and die.
+ * @param int   $status_code The HTTP status code to output.
+ */
+function wp_send_json_success( $data = null, $status_code = null ) {
 	$response = array( 'success' => true );
 
 	if ( isset( $data ) )
 		$response['data'] = $data;
 
-	wp_send_json( $response );
+	wp_send_json( $response, $status_code );
 }
 
 /**
  * Send a JSON response back to an Ajax request, indicating failure.
  *
- * If the `$data` parameter is a {@see WP_Error} object, the errors
+ * If the `$data` parameter is a WP_Error object, the errors
  * within the object are processed and output as an array of error
  * codes and corresponding messages. All other types are output
  * without further processing.
  *
  * @since 3.5.0
- * @since 4.1.0 The `$data` parameter is now processed if a {@see WP_Error}
- *              object is passed in.
- *
- * @param mixed $data Data to encode as JSON, then print and die.
- */
-function wp_send_json_error( $data = null ) {
+ * @since 4.1.0 The `$data` parameter is now processed if a WP_Error object is passed in.
+ * @since 4.7.0 The `$status_code` parameter was added.
+ *
+ * @param mixed $data        Data to encode as JSON, then print and die.
+ * @param int   $status_code The HTTP status code to output.
+ */
+function wp_send_json_error( $data = null, $status_code = null ) {
 	$response = array( 'success' => false );
 
 	if ( isset( $data ) ) {
@@ -2842,7 +3243,29 @@
 		}
 	}
 
-	wp_send_json( $response );
+	wp_send_json( $response, $status_code );
+}
+
+/**
+ * Checks that a JSONP callback is a valid JavaScript callback.
+ *
+ * Only allows alphanumeric characters and the dot character in callback
+ * function names. This helps to mitigate XSS attacks caused by directly
+ * outputting user input.
+ *
+ * @since 4.6.0
+ *
+ * @param string $callback Supplied JSONP callback function.
+ * @return bool True if valid callback, otherwise false.
+ */
+function wp_check_jsonp_callback( $callback ) {
+	if ( ! is_string( $callback ) ) {
+		return false;
+	}
+
+	preg_replace( '/[^\w\.]/', '', $callback, -1, $illegal_char_count );
+
+	return 0 === $illegal_char_count;
 }
 
 /**
@@ -2888,6 +3311,16 @@
 }
 
 /**
+ * Delete the fresh site option.
+ *
+ * @since 4.7.0
+ * @access private
+ */
+function _delete_option_fresh_site() {
+	update_option( 'fresh_site', '0' );
+}
+
+/**
  * Set the localized direction for MCE plugin.
  *
  * Will only set the direction to 'rtl', if the WordPress locale has
@@ -2896,28 +3329,29 @@
  * Fills in the 'directionality' setting, enables the 'directionality'
  * plugin, and adds the 'ltr' button to 'toolbar1', formerly
  * 'theme_advanced_buttons1' array keys. These keys are then returned
- * in the $input (TinyMCE settings) array.
+ * in the $mce_init (TinyMCE settings) array.
  *
  * @since 2.1.0
  * @access private
  *
- * @param array $input MCE settings array.
+ * @param array $mce_init MCE settings array.
  * @return array Direction set for 'rtl', if needed by locale.
  */
-function _mce_set_direction( $input ) {
+function _mce_set_direction( $mce_init ) {
 	if ( is_rtl() ) {
-		$input['directionality'] = 'rtl';
-
-		if ( ! empty( $input['plugins'] ) && strpos( $input['plugins'], 'directionality' ) === false ) {
-			$input['plugins'] .= ',directionality';
+		$mce_init['directionality'] = 'rtl';
+		$mce_init['rtl_ui'] = true;
+
+		if ( ! empty( $mce_init['plugins'] ) && strpos( $mce_init['plugins'], 'directionality' ) === false ) {
+			$mce_init['plugins'] .= ',directionality';
 		}
 
-		if ( ! empty( $input['toolbar1'] ) && ! preg_match( '/\bltr\b/', $input['toolbar1'] ) ) {
-			$input['toolbar1'] .= ',ltr';
+		if ( ! empty( $mce_init['toolbar1'] ) && ! preg_match( '/\bltr\b/', $mce_init['toolbar1'] ) ) {
+			$mce_init['toolbar1'] .= ',ltr';
 		}
 	}
 
-	return $input;
+	return $mce_init;
 }
 
 
@@ -2957,7 +3391,7 @@
 		':twisted:' => "\xf0\x9f\x98\x88",
 		  ':arrow:' => "\xe2\x9e\xa1",
 		  ':shock:' => "\xf0\x9f\x98\xaf",
-		  ':smile:' => 'simple-smile.png',
+		  ':smile:' => "\xf0\x9f\x99\x82",
 		    ':???:' => "\xf0\x9f\x98\x95",
 		   ':cool:' => "\xf0\x9f\x98\x8e",
 		   ':evil:' => "\xf0\x9f\x91\xbf",
@@ -2965,17 +3399,17 @@
 		   ':idea:' => "\xf0\x9f\x92\xa1",
 		   ':oops:' => "\xf0\x9f\x98\xb3",
 		   ':razz:' => "\xf0\x9f\x98\x9b",
-		   ':roll:' => 'rolleyes.png',
+		   ':roll:' => "\xf0\x9f\x99\x84",
 		   ':wink:' => "\xf0\x9f\x98\x89",
 		    ':cry:' => "\xf0\x9f\x98\xa5",
 		    ':eek:' => "\xf0\x9f\x98\xae",
 		    ':lol:' => "\xf0\x9f\x98\x86",
 		    ':mad:' => "\xf0\x9f\x98\xa1",
-		    ':sad:' => 'frownie.png',
+		    ':sad:' => "\xf0\x9f\x99\x81",
 		      '8-)' => "\xf0\x9f\x98\x8e",
 		      '8-O' => "\xf0\x9f\x98\xaf",
-		      ':-(' => 'frownie.png',
-		      ':-)' => 'simple-smile.png',
+		      ':-(' => "\xf0\x9f\x99\x81",
+		      ':-)' => "\xf0\x9f\x99\x82",
 		      ':-?' => "\xf0\x9f\x98\x95",
 		      ':-D' => "\xf0\x9f\x98\x80",
 		      ':-P' => "\xf0\x9f\x98\x9b",
@@ -2986,8 +3420,8 @@
 		// This one transformation breaks regular text with frequency.
 		//     '8)' => "\xf0\x9f\x98\x8e",
 		       '8O' => "\xf0\x9f\x98\xaf",
-		       ':(' => 'frownie.png',
-		       ':)' => 'simple-smile.png',
+		       ':(' => "\xf0\x9f\x99\x81",
+		       ':)' => "\xf0\x9f\x99\x82",
 		       ':?' => "\xf0\x9f\x98\x95",
 		       ':D' => "\xf0\x9f\x98\x80",
 		       ':P' => "\xf0\x9f\x98\x9b",
@@ -3000,6 +3434,18 @@
 		);
 	}
 
+	/**
+	 * Filters all the smilies.
+	 *
+	 * This filter must be added before `smilies_init` is run, as
+	 * it is normally only run once to setup the smilies regex.
+	 *
+	 * @since 4.7.0
+	 *
+	 * @param array $wpsmiliestrans List of the smilies.
+	 */
+	$wpsmiliestrans = apply_filters('smilies', $wpsmiliestrans);
+
 	if (count($wpsmiliestrans) == 0) {
 		return;
 	}
@@ -3046,9 +3492,10 @@
  * to be merged into another array.
  *
  * @since 2.2.0
- *
- * @param string|array $args     Value to merge with $defaults
- * @param array        $defaults Optional. Array that serves as the defaults. Default empty.
+ * @since 2.3.0 `$args` can now also be an object.
+ *
+ * @param string|array|object $args     Value to merge with $defaults.
+ * @param array               $defaults Optional. Array that serves as the defaults. Default empty.
  * @return array Merged user defined values with defaults.
  */
 function wp_parse_args( $args, $defaults = '' ) {
@@ -3080,6 +3527,26 @@
 }
 
 /**
+ * Clean up an array, comma- or space-separated list of slugs.
+ *
+ * @since 4.7.0
+ *
+ * @param  array|string $list List of slugs.
+ * @return array Sanitized array of slugs.
+ */
+function wp_parse_slug_list( $list ) {
+	if ( ! is_array( $list ) ) {
+		$list = preg_split( '/[\s,]+/', $list );
+	}
+
+	foreach ( $list as $key => $value ) {
+		$list[ $key ] = sanitize_title( $value );
+	}
+
+	return array_unique( $list );
+}
+
+/**
  * Extract a slice of an array, given a list of keys.
  *
  * @since 3.1.0
@@ -3098,36 +3565,61 @@
 }
 
 /**
+ * Determines if the variable is a numeric-indexed array.
+ *
+ * @since 4.4.0
+ *
+ * @param mixed $data Variable to check.
+ * @return bool Whether the variable is a list.
+ */
+function wp_is_numeric_array( $data ) {
+	if ( ! is_array( $data ) ) {
+		return false;
+	}
+
+	$keys = array_keys( $data );
+	$string_keys = array_filter( $keys, 'is_string' );
+	return count( $string_keys ) === 0;
+}
+
+/**
  * Filters a list of objects, based on a set of key => value arguments.
  *
  * @since 3.0.0
+ * @since 4.7.0 Uses WP_List_Util class.
  *
  * @param array       $list     An array of objects to filter
  * @param array       $args     Optional. An array of key => value arguments to match
  *                              against each object. Default empty array.
  * @param string      $operator Optional. The logical operation to perform. 'or' means
  *                              only one element from the array needs to match; 'and'
- *                              means all elements must match. Default 'and'.
+ *                              means all elements must match; 'not' means no elements may
+ *                              match. Default 'and'.
  * @param bool|string $field    A field from the object to place instead of the entire object.
  *                              Default false.
  * @return array A list of objects or object fields.
  */
 function wp_filter_object_list( $list, $args = array(), $operator = 'and', $field = false ) {
-	if ( ! is_array( $list ) )
+	if ( ! is_array( $list ) ) {
 		return array();
-
-	$list = wp_list_filter( $list, $args, $operator );
-
-	if ( $field )
-		$list = wp_list_pluck( $list, $field );
-
-	return $list;
+	}
+
+	$util = new WP_List_Util( $list );
+
+	$util->filter( $args, $operator );
+
+	if ( $field ) {
+		$util->pluck( $field );
+	}
+
+	return $util->get_output();
 }
 
 /**
  * Filters a list of objects, based on a set of key => value arguments.
  *
  * @since 3.1.0
+ * @since 4.7.0 Uses WP_List_Util class.
  *
  * @param array  $list     An array of objects to filter.
  * @param array  $args     Optional. An array of key => value arguments to match
@@ -3139,33 +3631,12 @@
  * @return array Array of found values.
  */
 function wp_list_filter( $list, $args = array(), $operator = 'AND' ) {
-	if ( ! is_array( $list ) )
+	if ( ! is_array( $list ) ) {
 		return array();
-
-	if ( empty( $args ) )
-		return $list;
-
-	$operator = strtoupper( $operator );
-	$count = count( $args );
-	$filtered = array();
-
-	foreach ( $list as $key => $obj ) {
-		$to_match = (array) $obj;
-
-		$matched = 0;
-		foreach ( $args as $m_key => $m_value ) {
-			if ( array_key_exists( $m_key, $to_match ) && $m_value == $to_match[ $m_key ] )
-				$matched++;
-		}
-
-		if ( ( 'AND' == $operator && $matched == $count )
-		  || ( 'OR' == $operator && $matched > 0 )
-		  || ( 'NOT' == $operator && 0 == $matched ) ) {
-			$filtered[$key] = $obj;
-		}
-	}
-
-	return $filtered;
+	}
+
+	$util = new WP_List_Util( $list );
+	return $util->filter( $args, $operator );
 }
 
 /**
@@ -3176,6 +3647,7 @@
  *
  * @since 3.1.0
  * @since 4.0.0 $index_key parameter added.
+ * @since 4.7.0 Uses WP_List_Util class.
  *
  * @param array      $list      List of objects or arrays
  * @param int|string $field     Field from the object to place instead of the entire object
@@ -3186,43 +3658,30 @@
  *               `$list` will be preserved in the results.
  */
 function wp_list_pluck( $list, $field, $index_key = null ) {
-	if ( ! $index_key ) {
-		/*
-		 * This is simple. Could at some point wrap array_column()
-		 * if we knew we had an array of arrays.
-		 */
-		foreach ( $list as $key => $value ) {
-			if ( is_object( $value ) ) {
-				$list[ $key ] = $value->$field;
-			} else {
-				$list[ $key ] = $value[ $field ];
-			}
-		}
-		return $list;
-	}
-
-	/*
-	 * When index_key is not set for a particular item, push the value
-	 * to the end of the stack. This is how array_column() behaves.
-	 */
-	$newlist = array();
-	foreach ( $list as $value ) {
-		if ( is_object( $value ) ) {
-			if ( isset( $value->$index_key ) ) {
-				$newlist[ $value->$index_key ] = $value->$field;
-			} else {
-				$newlist[] = $value->$field;
-			}
-		} else {
-			if ( isset( $value[ $index_key ] ) ) {
-				$newlist[ $value[ $index_key ] ] = $value[ $field ];
-			} else {
-				$newlist[] = $value[ $field ];
-			}
-		}
-	}
-
-	return $newlist;
+	$util = new WP_List_Util( $list );
+	return $util->pluck( $field, $index_key );
+}
+
+/**
+ * Sorts a list of objects, based on one or more orderby arguments.
+ *
+ * @since 4.7.0
+ *
+ * @param array        $list          An array of objects to filter.
+ * @param string|array $orderby       Optional. Either the field name to order by or an array
+ *                                    of multiple orderby fields as $orderby => $order.
+ * @param string       $order         Optional. Either 'ASC' or 'DESC'. Only used if $orderby
+ *                                    is a string.
+ * @param bool         $preserve_keys Optional. Whether to preserve keys. Default false.
+ * @return array The sorted array.
+ */
+function wp_list_sort( $list, $orderby = array(), $order = 'ASC', $preserve_keys = false ) {
+	if ( ! is_array( $list ) ) {
+		return array();
+	}
+
+	$util = new WP_List_Util( $list );
+	return $util->sort( $orderby, $order, $preserve_keys );
 }
 
 /**
@@ -3235,7 +3694,7 @@
  */
 function wp_maybe_load_widgets() {
 	/**
-	 * Filter whether to load the Widgets library.
+	 * Filters whether to load the Widgets library.
 	 *
 	 * Passing a falsey value to the filter will effectively short-circuit
 	 * the Widgets library from loading.
@@ -3258,6 +3717,8 @@
  * Append the Widgets menu to the themes main menu.
  *
  * @since 2.2.0
+ *
+ * @global array $submenu
  */
 function wp_widgets_add_menu() {
 	global $submenu;
@@ -3312,7 +3773,7 @@
 	}
 
 	// If installing or in the admin, provide the verbose message.
-	if ( defined('WP_INSTALLING') || defined('WP_ADMIN') )
+	if ( wp_installing() || defined( 'WP_ADMIN' ) )
 		wp_die($wpdb->error);
 
 	// Otherwise, be terse.
@@ -3350,11 +3811,11 @@
 /**
  * Mark a function as deprecated and inform when it has been used.
  *
- * There is a hook deprecated_function_run that will be called that can be used
+ * There is a {@see 'hook deprecated_function_run'} that will be called that can be used
  * to get the backtrace up to what file and function called the deprecated
  * function.
  *
- * The current behavior is to trigger a user error if WP_DEBUG is true.
+ * The current behavior is to trigger a user error if `WP_DEBUG` is true.
  *
  * This function is to be used in every function that is deprecated.
  *
@@ -3379,7 +3840,7 @@
 	do_action( 'deprecated_function_run', $function, $replacement, $version );
 
 	/**
-	 * Filter whether to trigger an error for deprecated functions.
+	 * Filters whether to trigger an error for deprecated functions.
 	 *
 	 * @since 2.5.0
 	 *
@@ -3387,27 +3848,98 @@
 	 */
 	if ( WP_DEBUG && apply_filters( 'deprecated_function_trigger_error', true ) ) {
 		if ( function_exists( '__' ) ) {
-			if ( ! is_null( $replacement ) )
+			if ( ! is_null( $replacement ) ) {
+				/* translators: 1: PHP function name, 2: version number, 3: alternative function name */
 				trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.'), $function, $version, $replacement ) );
-			else
+			} else {
+				/* translators: 1: PHP function name, 2: version number */
 				trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.'), $function, $version ) );
+			}
 		} else {
-			if ( ! is_null( $replacement ) )
+			if ( ! is_null( $replacement ) ) {
 				trigger_error( sprintf( '%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.', $function, $version, $replacement ) );
-			else
+			} else {
 				trigger_error( sprintf( '%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.', $function, $version ) );
+			}
 		}
 	}
 }
 
 /**
+ * Marks a constructor as deprecated and informs when it has been used.
+ *
+ * Similar to _deprecated_function(), but with different strings. Used to
+ * remove PHP4 style constructors.
+ *
+ * The current behavior is to trigger a user error if `WP_DEBUG` is true.
+ *
+ * This function is to be used in every PHP4 style constructor method that is deprecated.
+ *
+ * @since 4.3.0
+ * @since 4.5.0 Added the `$parent_class` parameter.
+ *
+ * @access private
+ *
+ * @param string $class        The class containing the deprecated constructor.
+ * @param string $version      The version of WordPress that deprecated the function.
+ * @param string $parent_class Optional. The parent class calling the deprecated constructor.
+ *                             Default empty string.
+ */
+function _deprecated_constructor( $class, $version, $parent_class = '' ) {
+
+	/**
+	 * Fires when a deprecated constructor is called.
+	 *
+	 * @since 4.3.0
+	 * @since 4.5.0 Added the `$parent_class` parameter.
+	 *
+	 * @param string $class        The class containing the deprecated constructor.
+	 * @param string $version      The version of WordPress that deprecated the function.
+	 * @param string $parent_class The parent class calling the deprecated constructor.
+	 */
+	do_action( 'deprecated_constructor_run', $class, $version, $parent_class );
+
+	/**
+	 * Filters whether to trigger an error for deprecated functions.
+	 *
+	 * `WP_DEBUG` must be true in addition to the filter evaluating to true.
+	 *
+	 * @since 4.3.0
+	 *
+	 * @param bool $trigger Whether to trigger the error for deprecated functions. Default true.
+	 */
+	if ( WP_DEBUG && apply_filters( 'deprecated_constructor_trigger_error', true ) ) {
+		if ( function_exists( '__' ) ) {
+			if ( ! empty( $parent_class ) ) {
+				/* translators: 1: PHP class name, 2: PHP parent class name, 3: version number, 4: __construct() method */
+				trigger_error( sprintf( __( 'The called constructor method for %1$s in %2$s is <strong>deprecated</strong> since version %3$s! Use %4$s instead.' ),
+					$class, $parent_class, $version, '<pre>__construct()</pre>' ) );
+			} else {
+				/* translators: 1: PHP class name, 2: version number, 3: __construct() method */
+				trigger_error( sprintf( __( 'The called constructor method for %1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.' ),
+					$class, $version, '<pre>__construct()</pre>' ) );
+			}
+		} else {
+			if ( ! empty( $parent_class ) ) {
+				trigger_error( sprintf( 'The called constructor method for %1$s in %2$s is <strong>deprecated</strong> since version %3$s! Use %4$s instead.',
+					$class, $parent_class, $version, '<pre>__construct()</pre>' ) );
+			} else {
+				trigger_error( sprintf( 'The called constructor method for %1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.',
+					$class, $version, '<pre>__construct()</pre>' ) );
+			}
+		}
+	}
+
+}
+
+/**
  * Mark a file as deprecated and inform when it has been used.
  *
- * There is a hook deprecated_file_included that will be called that can be used
+ * There is a hook {@see 'deprecated_file_included'} that will be called that can be used
  * to get the backtrace up to what file and function included the deprecated
  * file.
  *
- * The current behavior is to trigger a user error if WP_DEBUG is true.
+ * The current behavior is to trigger a user error if `WP_DEBUG` is true.
  *
  * This function is to be used in every file that is deprecated.
  *
@@ -3435,7 +3967,7 @@
 	do_action( 'deprecated_file_included', $file, $replacement, $version, $message );
 
 	/**
-	 * Filter whether to trigger an error for deprecated files.
+	 * Filters whether to trigger an error for deprecated files.
 	 *
 	 * @since 2.5.0
 	 *
@@ -3444,15 +3976,19 @@
 	if ( WP_DEBUG && apply_filters( 'deprecated_file_trigger_error', true ) ) {
 		$message = empty( $message ) ? '' : ' ' . $message;
 		if ( function_exists( '__' ) ) {
-			if ( ! is_null( $replacement ) )
+			if ( ! is_null( $replacement ) ) {
+				/* translators: 1: PHP file name, 2: version number, 3: alternative file name */
 				trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.'), $file, $version, $replacement ) . $message );
-			else
+			} else {
+				/* translators: 1: PHP file name, 2: version number */
 				trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.'), $file, $version ) . $message );
+			}
 		} else {
-			if ( ! is_null( $replacement ) )
+			if ( ! is_null( $replacement ) ) {
 				trigger_error( sprintf( '%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.', $file, $version, $replacement ) . $message );
-			else
+			} else {
 				trigger_error( sprintf( '%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.', $file, $version ) . $message );
+			}
 		}
 	}
 }
@@ -3465,7 +4001,7 @@
  * For example:
  *
  *     if ( ! empty( $deprecated ) ) {
- *         _deprecated_argument( __FUNCTION__, '3.0' );
+ *         _deprecated_argument( __FUNCTION__, '3.0.0' );
  *     }
  *
  *
@@ -3496,7 +4032,7 @@
 	do_action( 'deprecated_argument_run', $function, $message, $version );
 
 	/**
-	 * Filter whether to trigger an error for deprecated arguments.
+	 * Filters whether to trigger an error for deprecated arguments.
 	 *
 	 * @since 3.0.0
 	 *
@@ -3504,15 +4040,71 @@
 	 */
 	if ( WP_DEBUG && apply_filters( 'deprecated_argument_trigger_error', true ) ) {
 		if ( function_exists( '__' ) ) {
-			if ( ! is_null( $message ) )
+			if ( ! is_null( $message ) ) {
+				/* translators: 1: PHP function name, 2: version number, 3: optional message regarding the change */
 				trigger_error( sprintf( __('%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s! %3$s'), $function, $version, $message ) );
-			else
+			} else {
+				/* translators: 1: PHP function name, 2: version number */
 				trigger_error( sprintf( __('%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s with no alternative available.'), $function, $version ) );
+			}
 		} else {
-			if ( ! is_null( $message ) )
+			if ( ! is_null( $message ) ) {
 				trigger_error( sprintf( '%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s! %3$s', $function, $version, $message ) );
-			else
+			} else {
 				trigger_error( sprintf( '%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s with no alternative available.', $function, $version ) );
+			}
+		}
+	}
+}
+
+/**
+ * Marks a deprecated action or filter hook as deprecated and throws a notice.
+ *
+ * Use the {@see 'deprecated_hook_run'} action to get the backtrace describing where
+ * the deprecated hook was called.
+ *
+ * Default behavior is to trigger a user error if `WP_DEBUG` is true.
+ *
+ * This function is called by the do_action_deprecated() and apply_filters_deprecated()
+ * functions, and so generally does not need to be called directly.
+ *
+ * @since 4.6.0
+ * @access private
+ *
+ * @param string $hook        The hook that was used.
+ * @param string $version     The version of WordPress that deprecated the hook.
+ * @param string $replacement Optional. The hook that should have been used.
+ * @param string $message     Optional. A message regarding the change.
+ */
+function _deprecated_hook( $hook, $version, $replacement = null, $message = null ) {
+	/**
+	 * Fires when a deprecated hook is called.
+	 *
+	 * @since 4.6.0
+	 *
+	 * @param string $hook        The hook that was called.
+	 * @param string $replacement The hook that should be used as a replacement.
+	 * @param string $version     The version of WordPress that deprecated the argument used.
+	 * @param string $message     A message regarding the change.
+	 */
+	do_action( 'deprecated_hook_run', $hook, $replacement, $version, $message );
+
+	/**
+	 * Filters whether to trigger deprecated hook errors.
+	 *
+	 * @since 4.6.0
+	 *
+	 * @param bool $trigger Whether to trigger deprecated hook errors. Requires
+	 *                      `WP_DEBUG` to be defined true.
+	 */
+	if ( WP_DEBUG && apply_filters( 'deprecated_hook_trigger_error', true ) ) {
+		$message = empty( $message ) ? '' : ' ' . $message;
+		if ( ! is_null( $replacement ) ) {
+			/* translators: 1: WordPress hook name, 2: version number, 3: alternative hook name */
+			trigger_error( sprintf( __( '%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.' ), $hook, $version, $replacement ) . $message );
+		} else {
+			/* translators: 1: WordPress hook name, 2: version number */
+			trigger_error( sprintf( __( '%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.' ), $hook, $version ) . $message );
 		}
 	}
 }
@@ -3520,11 +4112,11 @@
 /**
  * Mark something as being incorrectly called.
  *
- * There is a hook doing_it_wrong_run that will be called that can be used
+ * There is a hook {@see 'doing_it_wrong_run'} that will be called that can be used
  * to get the backtrace up to what file and function called the deprecated
  * function.
  *
- * The current behavior is to trigger a user error if WP_DEBUG is true.
+ * The current behavior is to trigger a user error if `WP_DEBUG` is true.
  *
  * @since 3.1.0
  * @access private
@@ -3547,7 +4139,7 @@
 	do_action( 'doing_it_wrong_run', $function, $message, $version );
 
 	/**
-	 * Filter whether to trigger an error for _doing_it_wrong() calls.
+	 * Filters whether to trigger an error for _doing_it_wrong() calls.
 	 *
 	 * @since 3.1.0
 	 *
@@ -3555,12 +4147,27 @@
 	 */
 	if ( WP_DEBUG && apply_filters( 'doing_it_wrong_trigger_error', true ) ) {
 		if ( function_exists( '__' ) ) {
-			$version = is_null( $version ) ? '' : sprintf( __( '(This message was added in version %s.)' ), $version );
-			$message .= ' ' . __( 'Please see <a href="https://codex.wordpress.org/Debugging_in_WordPress">Debugging in WordPress</a> for more information.' );
+			if ( is_null( $version ) ) {
+				$version = '';
+			} else {
+				/* translators: %s: version number */
+				$version = sprintf( __( '(This message was added in version %s.)' ), $version );
+			}
+			/* translators: %s: Codex URL */
+			$message .= ' ' . sprintf( __( 'Please see <a href="%s">Debugging in WordPress</a> for more information.' ),
+				__( 'https://codex.wordpress.org/Debugging_in_WordPress' )
+			);
+			/* translators: Developer debugging message. 1: PHP function name, 2: Explanatory message, 3: Version information message */
 			trigger_error( sprintf( __( '%1$s was called <strong>incorrectly</strong>. %2$s %3$s' ), $function, $message, $version ) );
 		} else {
-			$version = is_null( $version ) ? '' : sprintf( '(This message was added in version %s.)', $version );
-			$message .= ' Please see <a href="https://codex.wordpress.org/Debugging_in_WordPress">Debugging in WordPress</a> for more information.';
+			if ( is_null( $version ) ) {
+				$version = '';
+			} else {
+				$version = sprintf( '(This message was added in version %s.)', $version );
+			}
+			$message .= sprintf( ' Please see <a href="%s">Debugging in WordPress</a> for more information.',
+				'https://codex.wordpress.org/Debugging_in_WordPress'
+			);
 			trigger_error( sprintf( '%1$s was called <strong>incorrectly</strong>. %2$s %3$s', $function, $message, $version ) );
 		}
 	}
@@ -3584,6 +4191,8 @@
  *
  * @since 2.5.0
  *
+ * @global bool $is_apache
+ *
  * @param string $mod     The module, e.g. mod_rewrite.
  * @param bool   $default Optional. The default return value if the module is not found. Default false.
  * @return bool Whether the specified module is loaded.
@@ -3613,6 +4222,8 @@
  *
  * @since 2.8.0
  *
+ * @global bool $is_iis7
+ *
  * @return bool Whether IIS7 supports permalinks.
  */
 function iis7_supports_permalinks() {
@@ -3629,11 +4240,11 @@
 		 * Lastly we make sure that PHP is running via FastCGI. This is important because if it runs
 		 * via ISAPI then pretty permalinks will not work.
 		 */
-		$supports_permalinks = class_exists('DOMDocument') && isset($_SERVER['IIS_UrlRewriteModule']) && ( PHP_SAPI == 'cgi-fcgi' );
+		$supports_permalinks = class_exists( 'DOMDocument', false ) && isset($_SERVER['IIS_UrlRewriteModule']) && ( PHP_SAPI == 'cgi-fcgi' );
 	}
 
 	/**
-	 * Filter whether IIS 7+ supports pretty permalinks.
+	 * Filters whether IIS 7+ supports pretty permalinks.
 	 *
 	 * @since 2.8.0
 	 *
@@ -3643,29 +4254,41 @@
 }
 
 /**
- * File validates against allowed set of defined rules.
- *
- * A return value of '1' means that the $file contains either '..' or './'. A
- * return value of '2' means that the $file contains ':' after the first
- * character. A return value of '3' means that the file is not in the allowed
- * files list.
+ * Validates a file name and path against an allowed set of rules.
+ *
+ * A return value of `1` means the file path contains directory traversal.
+ *
+ * A return value of `2` means the file path contains a Windows drive path.
+ *
+ * A return value of `3` means the file is not in the allowed files list.
  *
  * @since 1.2.0
  *
- * @param string $file File path.
- * @param array $allowed_files List of allowed files.
+ * @param string $file          File path.
+ * @param array  $allowed_files Optional. List of allowed files.
  * @return int 0 means nothing is wrong, greater than 0 means something was wrong.
  */
-function validate_file( $file, $allowed_files = '' ) {
-	if ( false !== strpos( $file, '..' ) )
+function validate_file( $file, $allowed_files = array() ) {
+	// `../` on its own is not allowed:
+	if ( '../' === $file ) {
+		return 1;
+	}
+
+	// More than one occurence of `../` is not allowed:
+	if ( preg_match_all( '#\.\./#', $file, $matches, PREG_SET_ORDER ) && ( count( $matches ) > 1 ) ) {
 		return 1;
-
-	if ( false !== strpos( $file, './' ) )
+	}
+
+	// `../` which does not occur at the end of the path is not allowed:
+	if ( false !== strpos( $file, '../' ) && '../' !== mb_substr( $file, -3, 3 ) ) {
 		return 1;
-
+	}
+
+	// Files not in the allowed file list are not allowed:
 	if ( ! empty( $allowed_files ) && ! in_array( $file, $allowed_files ) )
 		return 3;
 
+	// Absolute Windows drive paths are not allowed:
 	if (':' == substr( $file, 1, 1 ) )
 		return 2;
 
@@ -3673,43 +4296,12 @@
 }
 
 /**
- * Determine if SSL is used.
- *
- * @since 2.6.0
- *
- * @return bool True if SSL, false if not used.
- */
-function is_ssl() {
-	if ( isset($_SERVER['HTTPS']) ) {
-		if ( 'on' == strtolower($_SERVER['HTTPS']) )
-			return true;
-		if ( '1' == $_SERVER['HTTPS'] )
-			return true;
-	} elseif ( isset($_SERVER['SERVER_PORT']) && ( '443' == $_SERVER['SERVER_PORT'] ) ) {
-		return true;
-	}
-	return false;
-}
-
-/**
- * Whether SSL login should be forced.
- *
- * @since 2.6.0
- *
- * @see force_ssl_admin()
- *
- * @param string|bool $force Optional Whether to force SSL login. Default null.
- * @return bool True if forced, false if not forced.
- */
-function force_ssl_login( $force = null ) {
-	return force_ssl_admin( $force );
-}
-
-/**
  * Whether to force SSL used for the Administration Screens.
  *
  * @since 2.6.0
  *
+ * @staticvar bool $forced
+ *
  * @param string|bool $force Optional. Whether to force SSL in admin screens. Default null.
  * @return bool True if forced, false if not forced.
  */
@@ -3755,12 +4347,12 @@
 			if ( false !== strpos( $_SERVER['SCRIPT_FILENAME'], $abspath_fix ) ) {
 				// Request is hitting a file inside ABSPATH
 				$directory = str_replace( ABSPATH, '', $script_filename_dir );
-				// Strip off the sub directory, and any file/query paramss
+				// Strip off the sub directory, and any file/query params
 				$path = preg_replace( '#/' . preg_quote( $directory, '#' ) . '/[^/]*$#i', '' , $_SERVER['REQUEST_URI'] );
 			} elseif ( false !== strpos( $abspath_fix, $script_filename_dir ) ) {
 				// Request is hitting a file above ABSPATH
 				$subdirectory = substr( $abspath_fix, strpos( $abspath_fix, $script_filename_dir ) + strlen( $script_filename_dir ) );
-				// Strip off any file/query params from the path, appending the sub directory to the install
+				// Strip off any file/query params from the path, appending the sub directory to the installation
 				$path = preg_replace( '#/[^/]*$#i', '' , $_SERVER['REQUEST_URI'] ) . $subdirectory;
 			} else {
 				$path = $_SERVER['REQUEST_URI'];
@@ -3786,6 +4378,8 @@
  *
  * @since 3.3.0
  *
+ * @staticvar bool $_suspend
+ *
  * @param bool $suspend Optional. Suspends additions if true, re-enables them if false.
  * @return bool The current suspend setting
  */
@@ -3801,12 +4395,14 @@
 /**
  * Suspend cache invalidation.
  *
- * Turns cache invalidation on and off. Useful during imports where you don't wont to do
+ * Turns cache invalidation on and off. Useful during imports where you don't want to do
  * invalidations every time a post is inserted. Callers must be sure that what they are
  * doing won't lead to an inconsistent cache when invalidation is suspended.
  *
  * @since 2.7.0
  *
+ * @global bool $_wp_suspend_cache_invalidation
+ *
  * @param bool $suspend Optional. Whether to suspend or enable cache invalidation. Default true.
  * @return bool The current suspend setting.
  */
@@ -3822,27 +4418,52 @@
  * Determine whether a site is the main site of the current network.
  *
  * @since 3.0.0
- *
- * @param int $site_id Optional. Site ID to test. Defaults to current site.
- *                     Defaults to current site.
+ * @since 4.9.0 The $network_id parameter has been added.
+ *
+ * @param int $site_id    Optional. Site ID to test. Defaults to current site.
+ * @param int $network_id Optional. Network ID of the network to check for.
+ *                        Defaults to current network.
  * @return bool True if $site_id is the main site of the network, or if not
  *              running Multisite.
  */
-function is_main_site( $site_id = null ) {
-	// This is the current network's information; 'site' is old terminology.
-	global $current_site;
-
-	if ( ! is_multisite() )
+function is_main_site( $site_id = null, $network_id = null ) {
+	if ( ! is_multisite() ) {
 		return true;
-
-	if ( ! $site_id )
+	}
+
+	if ( ! $site_id ) {
 		$site_id = get_current_blog_id();
-
-	return (int) $site_id === (int) $current_site->blog_id;
+	}
+
+	$site_id = (int) $site_id;
+
+	return $site_id === get_main_site_id( $network_id );
 }
 
 /**
- * Determine whether a network is the main network of the Multisite install.
+ * Gets the main site ID.
+ *
+ * @since 4.9.0
+ *
+ * @param int $network_id Optional. The ID of the network for which to get the main site.
+ *                        Defaults to the current network.
+ * @return int The ID of the main site.
+ */
+function get_main_site_id( $network_id = null ) {
+	if ( ! is_multisite() ) {
+		return get_current_blog_id();
+	}
+
+	$network = get_network( $network_id );
+	if ( ! $network ) {
+		return 0;
+	}
+
+	return $network->site_id;
+}
+
+/**
+ * Determine whether a network is the main network of the Multisite installation.
  *
  * @since 3.7.0
  *
@@ -3850,32 +4471,51 @@
  * @return bool True if $network_id is the main network, or if not running Multisite.
  */
 function is_main_network( $network_id = null ) {
-	global $wpdb;
-
-	if ( ! is_multisite() )
+	if ( ! is_multisite() ) {
 		return true;
-
-	$current_network_id = (int) get_current_site()->id;
-
-	if ( ! $network_id )
-		$network_id = $current_network_id;
+	}
+
+	if ( null === $network_id ) {
+		$network_id = get_current_network_id();
+	}
+
 	$network_id = (int) $network_id;
 
-	if ( defined( 'PRIMARY_NETWORK_ID' ) )
-		return $network_id === (int) PRIMARY_NETWORK_ID;
-
-	if ( 1 === $current_network_id )
-		return $network_id === $current_network_id;
-
-	$primary_network_id = (int) wp_cache_get( 'primary_network_id', 'site-options' );
-
-	if ( $primary_network_id )
-		return $network_id === $primary_network_id;
-
-	$primary_network_id = (int) $wpdb->get_var( "SELECT id FROM $wpdb->site ORDER BY id LIMIT 1" );
-	wp_cache_add( 'primary_network_id', $primary_network_id, 'site-options' );
-
-	return $network_id === $primary_network_id;
+	return ( $network_id === get_main_network_id() );
+}
+
+/**
+ * Get the main network ID.
+ *
+ * @since 4.3.0
+ *
+ * @return int The ID of the main network.
+ */
+function get_main_network_id() {
+	if ( ! is_multisite() ) {
+		return 1;
+	}
+
+	$current_network = get_network();
+
+	if ( defined( 'PRIMARY_NETWORK_ID' ) ) {
+		$main_network_id = PRIMARY_NETWORK_ID;
+	} elseif ( isset( $current_network->id ) && 1 === (int) $current_network->id ) {
+		// If the current network has an ID of 1, assume it is the main network.
+		$main_network_id = 1;
+	} else {
+		$_networks = get_networks( array( 'fields' => 'ids', 'number' => 1 ) );
+		$main_network_id = array_shift( $_networks );
+	}
+
+	/**
+	 * Filters the main network ID.
+	 *
+	 * @since 4.3.0
+	 *
+	 * @param int $main_network_id The ID of the main network.
+	 */
+	return (int) apply_filters( 'get_main_network_id', $main_network_id );
 }
 
 /**
@@ -3883,6 +4523,8 @@
  *
  * @since 3.0.0
  *
+ * @staticvar bool $global_terms
+ *
  * @return bool True if multisite and global terms enabled.
  */
 function global_terms_enabled() {
@@ -3893,14 +4535,14 @@
 	if ( is_null( $global_terms ) ) {
 
 		/**
-		 * Filter whether global terms are enabled.
+		 * Filters whether global terms are enabled.
 		 *
 		 * Passing a non-null value to the filter will effectively short-circuit the function,
 		 * returning the value of the 'global_terms_enabled' site option instead.
 		 *
 		 * @since 3.0.0
 		 *
-		 * @param null $anbled Whether global terms are enabled.
+		 * @param null $enabled Whether global terms are enabled.
 		 */
 		$filter = apply_filters( 'global_terms_enabled', null );
 		if ( ! is_null( $filter ) )
@@ -3918,7 +4560,7 @@
  *
  * @since 2.8.0
  *
- * @return float|bool Timezone GMT offset, false otherwise.
+ * @return float|false Timezone GMT offset, false otherwise.
  */
 function wp_timezone_override_offset() {
 	if ( !$timezone_string = get_option( 'timezone_string' ) ) {
@@ -3985,19 +4627,25 @@
  * Gives a nicely-formatted list of timezone strings.
  *
  * @since 2.9.0
+ * @since 4.7.0 Added the `$locale` parameter.
+ *
+ * @staticvar bool $mo_loaded
+ * @staticvar string $locale_loaded
  *
  * @param string $selected_zone Selected timezone.
+ * @param string $locale        Optional. Locale to load the timezones in. Default current site locale.
  * @return string
  */
-function wp_timezone_choice( $selected_zone ) {
-	static $mo_loaded = false;
+function wp_timezone_choice( $selected_zone, $locale = null ) {
+	static $mo_loaded = false, $locale_loaded = null;
 
 	$continents = array( 'Africa', 'America', 'Antarctica', 'Arctic', 'Asia', 'Atlantic', 'Australia', 'Europe', 'Indian', 'Pacific');
 
-	// Load translations for continents and cities
-	if ( !$mo_loaded ) {
-		$locale = get_locale();
-		$mofile = WP_LANG_DIR . '/continents-cities-' . $locale . '.mo';
+	// Load translations for continents and cities.
+	if ( ! $mo_loaded || $locale !== $locale_loaded ) {
+		$locale_loaded = $locale ? $locale : get_locale();
+		$mofile = WP_LANG_DIR . '/continents-cities-' . $locale_loaded . '.mo';
+		unload_textdomain( 'continents-cities' );
 		load_textdomain( 'continents-cities', $mofile );
 		$mo_loaded = true;
 	}
@@ -4132,13 +4780,15 @@
  * The default value of `EMPTY_TRASH_DAYS` is 30 (days).
  *
  * @since 2.9.0
+ *
+ * @global wpdb $wpdb WordPress database abstraction object.
  */
 function wp_scheduled_delete() {
 	global $wpdb;
 
 	$delete_timestamp = time() - ( DAY_IN_SECONDS * EMPTY_TRASH_DAYS );
 
-	$posts_to_delete = $wpdb->get_results($wpdb->prepare("SELECT post_id FROM $wpdb->postmeta WHERE meta_key = '_wp_trash_meta_time' AND meta_value < '%d'", $delete_timestamp), ARRAY_A);
+	$posts_to_delete = $wpdb->get_results($wpdb->prepare("SELECT post_id FROM $wpdb->postmeta WHERE meta_key = '_wp_trash_meta_time' AND meta_value < %d", $delete_timestamp), ARRAY_A);
 
 	foreach ( (array) $posts_to_delete as $post ) {
 		$post_id = (int) $post['post_id'];
@@ -4155,7 +4805,7 @@
 		}
 	}
 
-	$comments_to_delete = $wpdb->get_results($wpdb->prepare("SELECT comment_id FROM $wpdb->commentmeta WHERE meta_key = '_wp_trash_meta_time' AND meta_value < '%d'", $delete_timestamp), ARRAY_A);
+	$comments_to_delete = $wpdb->get_results($wpdb->prepare("SELECT comment_id FROM $wpdb->commentmeta WHERE meta_key = '_wp_trash_meta_time' AND meta_value < %d", $delete_timestamp), ARRAY_A);
 
 	foreach ( (array) $comments_to_delete as $comment ) {
 		$comment_id = (int) $comment['comment_id'];
@@ -4168,7 +4818,7 @@
 			delete_comment_meta($comment_id, '_wp_trash_meta_time');
 			delete_comment_meta($comment_id, '_wp_trash_meta_status');
 		} else {
-			wp_delete_comment($comment_id);
+			wp_delete_comment( $del_comment );
 		}
 	}
 }
@@ -4189,7 +4839,7 @@
  *
  * @param string $file            Path to the file.
  * @param array  $default_headers List of headers, in the format array('HeaderKey' => 'Header Name').
- * @param string $context         Optional. If specified adds filter hook "extra_{$context}_headers".
+ * @param string $context         Optional. If specified adds filter hook {@see 'extra_$context_headers'}.
  *                                Default empty.
  * @return array Array of file headers in `HeaderKey => Header Value` format.
  */
@@ -4207,7 +4857,7 @@
 	$file_data = str_replace( "\r", "\n", $file_data );
 
 	/**
-	 * Filter extra file headers by context.
+	 * Filters extra file headers by context.
 	 *
 	 * The dynamic portion of the hook name, `$context`, refers to
 	 * the context where extra headers might be loaded.
@@ -4242,7 +4892,7 @@
  *
  * @see __return_false()
  *
- * @return bool True.
+ * @return true True.
  */
 function __return_true() {
 	return true;
@@ -4257,7 +4907,7 @@
  *
  * @see __return_true()
  *
- * @return bool False.
+ * @return false False.
  */
 function __return_false() {
 	return false;
@@ -4322,8 +4972,8 @@
  *
  * @since 3.0.0
  *
- * @see http://blogs.msdn.com/ie/archive/2008/07/02/ie8-security-part-v-comprehensive-protection.aspx
- * @see http://src.chromium.org/viewvc/chrome?view=rev&revision=6985
+ * @see https://blogs.msdn.com/ie/archive/2008/07/02/ie8-security-part-v-comprehensive-protection.aspx
+ * @see https://src.chromium.org/viewvc/chrome?view=rev&revision=6985
  */
 function send_nosniff_header() {
 	@header( 'X-Content-Type-Options: nosniff' );
@@ -4360,7 +5010,7 @@
  * @since 3.1.0
  * @access private
  *
- * @param callback $callback      Function that accepts ( ID, $callback_args ) and outputs parent_ID.
+ * @param callable $callback      Function that accepts ( ID, $callback_args ) and outputs parent_ID.
  * @param int      $start         The ID to start the loop check at.
  * @param int      $start_parent  The parent_ID of $start to use instead of calling $callback( $start ).
  *                                Use null to always use $callback
@@ -4385,7 +5035,7 @@
  * @since 3.1.0
  * @access private
  *
- * @param callback $callback      Function that accepts ( ID, callback_arg, ... ) and outputs parent_ID.
+ * @param callable $callback      Function that accepts ( ID, callback_arg, ... ) and outputs parent_ID.
  * @param int      $start         The ID to start the loop check at.
  * @param array    $override      Optional. An array of ( ID => parent_ID, ... ) to use instead of $callback.
  *                                Default empty array.
@@ -4438,26 +5088,34 @@
  * Retrieve a list of protocols to allow in HTML attributes.
  *
  * @since 3.3.0
+ * @since 4.3.0 Added 'webcal' to the protocols array.
+ * @since 4.7.0 Added 'urn' to the protocols array.
  *
  * @see wp_kses()
  * @see esc_url()
  *
- * @return array Array of allowed protocols.
+ * @staticvar array $protocols
+ *
+ * @return array Array of allowed protocols. Defaults to an array containing 'http', 'https',
+ *               'ftp', 'ftps', 'mailto', 'news', 'irc', 'gopher', 'nntp', 'feed', 'telnet',
+ *               'mms', 'rtsp', 'svn', 'tel', 'fax', 'xmpp', 'webcal', and 'urn'.
  */
 function wp_allowed_protocols() {
-	static $protocols;
+	static $protocols = array();
 
 	if ( empty( $protocols ) ) {
-		$protocols = array( 'http', 'https', 'ftp', 'ftps', 'mailto', 'news', 'irc', 'gopher', 'nntp', 'feed', 'telnet', 'mms', 'rtsp', 'svn', 'tel', 'fax', 'xmpp' );
-
+		$protocols = array( 'http', 'https', 'ftp', 'ftps', 'mailto', 'news', 'irc', 'gopher', 'nntp', 'feed', 'telnet', 'mms', 'rtsp', 'svn', 'tel', 'fax', 'xmpp', 'webcal', 'urn' );
+	}
+
+	if ( ! did_action( 'wp_loaded' ) ) {
 		/**
-		 * Filter the list of protocols allowed in HTML attributes.
+		 * Filters the list of protocols allowed in HTML attributes.
 		 *
 		 * @since 3.0.0
 		 *
 		 * @param array $protocols Array of allowed protocols e.g. 'http', 'ftp', 'tel', and more.
 		 */
-		$protocols = apply_filters( 'kses_allowed_protocols', $protocols );
+		$protocols = array_unique( (array) apply_filters( 'kses_allowed_protocols', $protocols ) );
 	}
 
 	return $protocols;
@@ -4543,7 +5201,7 @@
  * @since 3.4.0
  * @access private
  *
- * @return bool true|false Whether the device is able to upload files.
+ * @return bool Whether the device is able to upload files.
  */
 function _device_can_upload() {
 	if ( ! wp_is_mobile() )
@@ -4563,12 +5221,20 @@
 /**
  * Test if a given path is a stream URL
  *
+ * @since 3.5.0
+ *
  * @param string $path The resource path or URL.
  * @return bool True if the path is a stream URL.
  */
 function wp_is_stream( $path ) {
-	$wrappers = stream_get_wrappers();
-	$wrappers_re = '(' . join('|', $wrappers) . ')';
+	if ( false === strpos( $path, '://' ) ) {
+		// $path isn't a stream
+		return false;
+	}
+
+	$wrappers    = stream_get_wrappers();
+	$wrappers    = array_map( 'preg_quote', $wrappers );
+	$wrappers_re = '(' . join( '|', $wrappers ) . ')';
 
 	return preg_match( "!^$wrappers_re://!", $path ) === 1;
 }
@@ -4588,7 +5254,7 @@
  */
 function wp_checkdate( $month, $day, $year, $source_date ) {
 	/**
-	 * Filter whether the given date is valid for the Gregorian calendar.
+	 * Filters whether the given date is valid for the Gregorian calendar.
 	 *
 	 * @since 3.5.0
 	 *
@@ -4604,7 +5270,7 @@
  * Can be disabled with remove_action( 'admin_enqueue_scripts', 'wp_auth_check_load' );
  *
  * This is disabled for certain screens where a login screen could cause an
- * inconvenient interruption. A filter called wp_auth_check_load can be used
+ * inconvenient interruption. A filter called {@see 'wp_auth_check_load'} can be used
  * for fine-grained control.
  *
  * @since 3.6.0
@@ -4621,7 +5287,7 @@
 	$show = ! in_array( $screen->id, $hidden );
 
 	/**
-	 * Filter whether to load the authentication check.
+	 * Filters whether to load the authentication check.
 	 *
 	 * Passing a falsey value to the filter will effectively short-circuit
 	 * loading the authentication check.
@@ -4651,7 +5317,7 @@
 	$same_domain = ( strpos( $login_url, $current_domain ) === 0 );
 
 	/**
-	 * Filter whether the authentication check originated at the same domain.
+	 * Filters whether the authentication check originated at the same domain.
 	 *
 	 * @since 3.6.0
 	 *
@@ -4664,12 +5330,16 @@
 	<div id="wp-auth-check-wrap" class="<?php echo $wrap_class; ?>">
 	<div id="wp-auth-check-bg"></div>
 	<div id="wp-auth-check">
-	<div class="wp-auth-check-close" tabindex="0" title="<?php esc_attr_e('Close'); ?>"></div>
+	<button type="button" class="wp-auth-check-close button-link"><span class="screen-reader-text"><?php _e( 'Close dialog' ); ?></span></button>
 	<?php
 
 	if ( $same_domain ) {
+		$login_src = add_query_arg( array(
+			'interim-login' => '1',
+			'wp_lang'       => get_user_locale(),
+		), $login_url );
 		?>
-		<div id="wp-auth-check-form" data-src="<?php echo esc_url( add_query_arg( array( 'interim-login' => 1 ), $login_url ) ); ?>"></div>
+		<div id="wp-auth-check-form" class="loading" data-src="<?php echo esc_url( $login_src ); ?>"></div>
 		<?php
 	}
 
@@ -4692,9 +5362,10 @@
  *
  * @since 3.6.0
  *
- * @param array|object $response  The Heartbeat response object or array.
- * @return array|object $response The Heartbeat response object or array with 'wp-auth-check'
- *                                value set.
+ * @global int $login_grace_period
+ *
+ * @param array $response  The Heartbeat response.
+ * @return array $response The Heartbeat response with 'wp-auth-check' value set.
  */
 function wp_auth_check( $response ) {
 	$response['wp-auth-check'] = is_user_logged_in() && empty( $GLOBALS['login_grace_period'] );
@@ -4736,13 +5407,15 @@
  * @return string The canonical form of the charset.
  */
 function _canonical_charset( $charset ) {
-	if ( 'UTF-8' === $charset || 'utf-8' === $charset || 'utf8' === $charset ||
-		'UTF8' === $charset )
+	if ( 'utf-8' === strtolower( $charset ) || 'utf8' === strtolower( $charset) ) {
+
 		return 'UTF-8';
-
-	if ( 'ISO-8859-1' === $charset || 'iso-8859-1' === $charset ||
-		'iso8859-1' === $charset || 'ISO8859-1' === $charset )
+	}
+
+	if ( 'iso-8859-1' === strtolower( $charset ) || 'iso8859-1' === strtolower( $charset ) ) {
+
 		return 'ISO-8859-1';
+	}
 
 	return $charset;
 }
@@ -4767,6 +5440,9 @@
  *
  * @see reset_mbstring_encoding()
  *
+ * @staticvar array $encodings
+ * @staticvar bool  $overloaded
+ *
  * @param bool $reset Optional. Whether to reset the encoding back to a previously-set encoding.
  *                    Default false.
  */
@@ -4834,14 +5510,568 @@
  */
 function wp_delete_file( $file ) {
 	/**
-	 * Filter the path of the file to delete.
+	 * Filters the path of the file to delete.
 	 *
 	 * @since 2.1.0
 	 *
-	 * @param string $medium Path to the file to delete.
+	 * @param string $file Path to the file to delete.
 	 */
 	$delete = apply_filters( 'wp_delete_file', $file );
 	if ( ! empty( $delete ) ) {
 		@unlink( $delete );
 	}
 }
+
+/**
+ * Deletes a file if its path is within the given directory.
+ *
+ * @since 4.9.7
+ *
+ * @param string $file      Absolute path to the file to delete.
+ * @param string $directory Absolute path to a directory.
+ * @return bool True on success, false on failure.
+ */
+function wp_delete_file_from_directory( $file, $directory ) {
+	$real_file = realpath( wp_normalize_path( $file ) );
+	$real_directory = realpath( wp_normalize_path( $directory ) );
+
+	if ( false === $real_file || false === $real_directory || strpos( wp_normalize_path( $real_file ), trailingslashit( wp_normalize_path( $real_directory ) ) ) !== 0 ) {
+		return false;
+	}
+
+	wp_delete_file( $file );
+
+	return true;
+}
+
+/**
+ * Outputs a small JS snippet on preview tabs/windows to remove `window.name` on unload.
+ *
+ * This prevents reusing the same tab for a preview when the user has navigated away.
+ *
+ * @since 4.3.0
+ *
+ * @global WP_Post $post
+ */
+function wp_post_preview_js() {
+	global $post;
+
+	if ( ! is_preview() || empty( $post ) ) {
+		return;
+	}
+
+	// Has to match the window name used in post_submit_meta_box()
+	$name = 'wp-preview-' . (int) $post->ID;
+
+	?>
+	<script>
+	( function() {
+		var query = document.location.search;
+
+		if ( query && query.indexOf( 'preview=true' ) !== -1 ) {
+			window.name = '<?php echo $name; ?>';
+		}
+
+		if ( window.addEventListener ) {
+			window.addEventListener( 'unload', function() { window.name = ''; }, false );
+		}
+	}());
+	</script>
+	<?php
+}
+
+/**
+ * Parses and formats a MySQL datetime (Y-m-d H:i:s) for ISO8601/RFC3339.
+ *
+ * Explicitly strips timezones, as datetimes are not saved with any timezone
+ * information. Including any information on the offset could be misleading.
+ *
+ * @since 4.4.0
+ *
+ * @param string $date_string Date string to parse and format.
+ * @return string Date formatted for ISO8601/RFC3339.
+ */
+function mysql_to_rfc3339( $date_string ) {
+	$formatted = mysql2date( 'c', $date_string, false );
+
+	// Strip timezone information
+	return preg_replace( '/(?:Z|[+-]\d{2}(?::\d{2})?)$/', '', $formatted );
+}
+
+/**
+ * Attempts to raise the PHP memory limit for memory intensive processes.
+ *
+ * Only allows raising the existing limit and prevents lowering it.
+ *
+ * @since 4.6.0
+ *
+ * @param string $context Optional. Context in which the function is called. Accepts either 'admin',
+ *                        'image', or an arbitrary other context. If an arbitrary context is passed,
+ *                        the similarly arbitrary {@see '{$context}_memory_limit'} filter will be
+ *                        invoked. Default 'admin'.
+ * @return bool|int|string The limit that was set or false on failure.
+ */
+function wp_raise_memory_limit( $context = 'admin' ) {
+	// Exit early if the limit cannot be changed.
+	if ( false === wp_is_ini_value_changeable( 'memory_limit' ) ) {
+		return false;
+	}
+
+	$current_limit     = @ini_get( 'memory_limit' );
+	$current_limit_int = wp_convert_hr_to_bytes( $current_limit );
+
+	if ( -1 === $current_limit_int ) {
+		return false;
+	}
+
+	$wp_max_limit     = WP_MAX_MEMORY_LIMIT;
+	$wp_max_limit_int = wp_convert_hr_to_bytes( $wp_max_limit );
+	$filtered_limit   = $wp_max_limit;
+
+	switch ( $context ) {
+		case 'admin':
+			/**
+			 * Filters the maximum memory limit available for administration screens.
+			 *
+			 * This only applies to administrators, who may require more memory for tasks
+			 * like updates. Memory limits when processing images (uploaded or edited by
+			 * users of any role) are handled separately.
+			 *
+			 * The `WP_MAX_MEMORY_LIMIT` constant specifically defines the maximum memory
+			 * limit available when in the administration back end. The default is 256M
+			 * (256 megabytes of memory) or the original `memory_limit` php.ini value if
+			 * this is higher.
+			 *
+			 * @since 3.0.0
+			 * @since 4.6.0 The default now takes the original `memory_limit` into account.
+			 *
+			 * @param int|string $filtered_limit The maximum WordPress memory limit. Accepts an integer
+			 *                                   (bytes), or a shorthand string notation, such as '256M'.
+			 */
+			$filtered_limit = apply_filters( 'admin_memory_limit', $filtered_limit );
+			break;
+
+		case 'image':
+			/**
+			 * Filters the memory limit allocated for image manipulation.
+			 *
+			 * @since 3.5.0
+			 * @since 4.6.0 The default now takes the original `memory_limit` into account.
+			 *
+			 * @param int|string $filtered_limit Maximum memory limit to allocate for images.
+			 *                                   Default `WP_MAX_MEMORY_LIMIT` or the original
+			 *                                   php.ini `memory_limit`, whichever is higher.
+			 *                                   Accepts an integer (bytes), or a shorthand string
+			 *                                   notation, such as '256M'.
+			 */
+			$filtered_limit = apply_filters( 'image_memory_limit', $filtered_limit );
+			break;
+
+		default:
+			/**
+			 * Filters the memory limit allocated for arbitrary contexts.
+			 *
+			 * The dynamic portion of the hook name, `$context`, refers to an arbitrary
+			 * context passed on calling the function. This allows for plugins to define
+			 * their own contexts for raising the memory limit.
+			 *
+			 * @since 4.6.0
+			 *
+			 * @param int|string $filtered_limit Maximum memory limit to allocate for images.
+			 *                                   Default '256M' or the original php.ini `memory_limit`,
+			 *                                   whichever is higher. Accepts an integer (bytes), or a
+			 *                                   shorthand string notation, such as '256M'.
+			 */
+			$filtered_limit = apply_filters( "{$context}_memory_limit", $filtered_limit );
+			break;
+	}
+
+	$filtered_limit_int = wp_convert_hr_to_bytes( $filtered_limit );
+
+	if ( -1 === $filtered_limit_int || ( $filtered_limit_int > $wp_max_limit_int && $filtered_limit_int > $current_limit_int ) ) {
+		if ( false !== @ini_set( 'memory_limit', $filtered_limit ) ) {
+			return $filtered_limit;
+		} else {
+			return false;
+		}
+	} elseif ( -1 === $wp_max_limit_int || $wp_max_limit_int > $current_limit_int ) {
+		if ( false !== @ini_set( 'memory_limit', $wp_max_limit ) ) {
+			return $wp_max_limit;
+		} else {
+			return false;
+		}
+	}
+
+	return false;
+}
+
+/**
+ * Generate a random UUID (version 4).
+ *
+ * @since 4.7.0
+ *
+ * @return string UUID.
+ */
+function wp_generate_uuid4() {
+	return sprintf( '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
+		mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ),
+		mt_rand( 0, 0xffff ),
+		mt_rand( 0, 0x0fff ) | 0x4000,
+		mt_rand( 0, 0x3fff ) | 0x8000,
+		mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff )
+	);
+}
+
+/**
+ * Validates that a UUID is valid.
+ *
+ * @since 4.9.0
+ *
+ * @param mixed $uuid    UUID to check.
+ * @param int   $version Specify which version of UUID to check against. Default is none, to accept any UUID version. Otherwise, only version allowed is `4`.
+ * @return bool The string is a valid UUID or false on failure.
+ */
+function wp_is_uuid( $uuid, $version = null ) {
+
+	if ( ! is_string( $uuid ) ) {
+		return false;
+	}
+
+	if ( is_numeric( $version ) ) {
+		if ( 4 !== (int) $version ) {
+			_doing_it_wrong( __FUNCTION__, __( 'Only UUID V4 is supported at this time.' ), '4.9.0' );
+			return false;
+		}
+		$regex = '/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/';
+	} else {
+		$regex = '/^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/';
+	}
+
+	return (bool) preg_match( $regex, $uuid );
+}
+
+/**
+ * Get last changed date for the specified cache group.
+ *
+ * @since 4.7.0
+ *
+ * @param string $group Where the cache contents are grouped.
+ *
+ * @return string $last_changed UNIX timestamp with microseconds representing when the group was last changed.
+ */
+function wp_cache_get_last_changed( $group ) {
+	$last_changed = wp_cache_get( 'last_changed', $group );
+
+	if ( ! $last_changed ) {
+		$last_changed = microtime();
+		wp_cache_set( 'last_changed', $last_changed, $group );
+	}
+
+	return $last_changed;
+}
+
+/**
+ * Send an email to the old site admin email address when the site admin email address changes.
+ *
+ * @since 4.9.0
+ *
+ * @param string $old_email   The old site admin email address.
+ * @param string $new_email   The new site admin email address.
+ * @param string $option_name The relevant database option name.
+ */
+function wp_site_admin_email_change_notification( $old_email, $new_email, $option_name ) {
+	$send = true;
+
+	// Don't send the notification to the default 'admin_email' value.
+	if ( 'you@example.com' === $old_email ) {
+		$send = false;
+	}
+
+	/**
+	 * Filters whether to send the site admin email change notification email.
+	 *
+	 * @since 4.9.0
+	 *
+	 * @param bool   $send      Whether to send the email notification.
+	 * @param string $old_email The old site admin email address.
+	 * @param string $new_email The new site admin email address.
+	 */
+	$send = apply_filters( 'send_site_admin_email_change_email', $send, $old_email, $new_email );
+
+	if ( ! $send ) {
+		return;
+	}
+
+	/* translators: Do not translate OLD_EMAIL, NEW_EMAIL, SITENAME, SITEURL: those are placeholders. */
+	$email_change_text = __( 'Hi,
+
+This notice confirms that the admin email address was changed on ###SITENAME###.
+
+The new admin email address is ###NEW_EMAIL###.
+
+This email has been sent to ###OLD_EMAIL###
+
+Regards,
+All at ###SITENAME###
+###SITEURL###' );
+
+	$email_change_email = array(
+		'to'      => $old_email,
+		/* translators: Site admin email change notification email subject. %s: Site title */
+		'subject' => __( '[%s] Notice of Admin Email Change' ),
+		'message' => $email_change_text,
+		'headers' => '',
+	);
+	// get site name
+	$site_name = wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES );
+
+	/**
+	 * Filters the contents of the email notification sent when the site admin email address is changed.
+	 *
+	 * @since 4.9.0
+	 *
+	 * @param array $email_change_email {
+	 *            Used to build wp_mail().
+	 *
+	 *            @type string $to      The intended recipient.
+	 *            @type string $subject The subject of the email.
+	 *            @type string $message The content of the email.
+	 *                The following strings have a special meaning and will get replaced dynamically:
+	 *                - ###OLD_EMAIL### The old site admin email address.
+	 *                - ###NEW_EMAIL### The new site admin email address.
+	 *                - ###SITENAME###  The name of the site.
+	 *                - ###SITEURL###   The URL to the site.
+	 *            @type string $headers Headers.
+	 *        }
+	 * @param string $old_email The old site admin email address.
+	 * @param string $new_email The new site admin email address.
+	 */
+	$email_change_email = apply_filters( 'site_admin_email_change_email', $email_change_email, $old_email, $new_email );
+
+	$email_change_email['message'] = str_replace( '###OLD_EMAIL###', $old_email, $email_change_email['message'] );
+	$email_change_email['message'] = str_replace( '###NEW_EMAIL###', $new_email, $email_change_email['message'] );
+	$email_change_email['message'] = str_replace( '###SITENAME###',  $site_name, $email_change_email['message'] );
+	$email_change_email['message'] = str_replace( '###SITEURL###',   home_url(), $email_change_email['message'] );
+
+	wp_mail( $email_change_email['to'], sprintf(
+		$email_change_email['subject'],
+		$site_name
+	), $email_change_email['message'], $email_change_email['headers'] );
+}
+
+/**
+ * Return an anonymized IPv4 or IPv6 address.
+ *
+ * @since 4.9.6 Abstracted from `WP_Community_Events::get_unsafe_client_ip()`.
+ *
+ * @param  string $ip_addr        The IPv4 or IPv6 address to be anonymized.
+ * @param  bool   $ipv6_fallback  Optional. Whether to return the original IPv6 address if the needed functions
+ *                                to anonymize it are not present. Default false, return `::` (unspecified address).
+ * @return string  The anonymized IP address.
+ */
+function wp_privacy_anonymize_ip( $ip_addr, $ipv6_fallback = false ) {
+	// Detect what kind of IP address this is.
+	$ip_prefix = '';
+	$is_ipv6   = substr_count( $ip_addr, ':' ) > 1;
+	$is_ipv4   = ( 3 === substr_count( $ip_addr, '.' ) );
+
+	if ( $is_ipv6 && $is_ipv4 ) {
+		// IPv6 compatibility mode, temporarily strip the IPv6 part, and treat it like IPv4.
+		$ip_prefix = '::ffff:';
+		$ip_addr   = preg_replace( '/^\[?[0-9a-f:]*:/i', '', $ip_addr );
+		$ip_addr   = str_replace( ']', '', $ip_addr );
+		$is_ipv6   = false;
+	}
+
+	if ( $is_ipv6 ) {
+		// IPv6 addresses will always be enclosed in [] if there's a port.
+		$left_bracket  = strpos( $ip_addr, '[' );
+		$right_bracket = strpos( $ip_addr, ']' );
+		$percent       = strpos( $ip_addr, '%' );
+		$netmask       = 'ffff:ffff:ffff:ffff:0000:0000:0000:0000';
+
+		// Strip the port (and [] from IPv6 addresses), if they exist.
+		if ( false !== $left_bracket && false !== $right_bracket ) {
+			$ip_addr = substr( $ip_addr, $left_bracket + 1, $right_bracket - $left_bracket - 1 );
+		} elseif ( false !== $left_bracket || false !== $right_bracket ) {
+			// The IP has one bracket, but not both, so it's malformed.
+			return '::';
+		}
+
+		// Strip the reachability scope.
+		if ( false !== $percent ) {
+			$ip_addr = substr( $ip_addr, 0, $percent );
+		}
+
+		// No invalid characters should be left.
+		if ( preg_match( '/[^0-9a-f:]/i', $ip_addr ) ) {
+			return '::';
+		}
+
+		// Partially anonymize the IP by reducing it to the corresponding network ID.
+		if ( function_exists( 'inet_pton' ) && function_exists( 'inet_ntop' ) ) {
+			$ip_addr = inet_ntop( inet_pton( $ip_addr ) & inet_pton( $netmask ) );
+			if ( false === $ip_addr) {
+				return '::';
+			}
+		} elseif ( ! $ipv6_fallback ) {
+			return '::';
+		}
+	} elseif ( $is_ipv4 ) {
+		// Strip any port and partially anonymize the IP.
+		$last_octet_position = strrpos( $ip_addr, '.' );
+		$ip_addr             = substr( $ip_addr, 0, $last_octet_position ) . '.0';
+	} else {
+		return '0.0.0.0';
+	}
+
+	// Restore the IPv6 prefix to compatibility mode addresses.
+	return $ip_prefix . $ip_addr;
+}
+
+/**
+ * Return uniform "anonymous" data by type.
+ *
+ * @since 4.9.6
+ *
+ * @param  string $type The type of data to be anonymized.
+ * @param  string $data Optional The data to be anonymized.
+ * @return string The anonymous data for the requested type.
+ */
+function wp_privacy_anonymize_data( $type, $data = '' ) {
+
+	switch ( $type ) {
+		case 'email':
+			$anonymous = 'deleted@site.invalid';
+			break;
+		case 'url':
+			$anonymous = 'https://site.invalid';
+			break;
+		case 'ip':
+			$anonymous = wp_privacy_anonymize_ip( $data );
+			break;
+		case 'date':
+			$anonymous = '0000-00-00 00:00:00';
+			break;
+		case 'text':
+			/* translators: deleted text */
+			$anonymous = __( '[deleted]' );
+			break;
+		case 'longtext':
+			/* translators: deleted long text */
+			$anonymous = __( 'This content was deleted by the author.' );
+			break;
+		default:
+			$anonymous = '';
+	}
+
+	/**
+	 * Filters the anonymous data for each type.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $anonymous Anonymized data.
+	 * @param string $type      Type of the data.
+	 * @param string $data      Original data.
+	 */
+	return apply_filters( 'wp_privacy_anonymize_data', $anonymous, $type, $data );
+}
+
+/**
+ * Returns the directory used to store personal data export files.
+ *
+ * @since 4.9.6
+ *
+ * @see wp_privacy_exports_url
+ *
+ * @return string Exports directory.
+ */
+function wp_privacy_exports_dir() {
+	$upload_dir  = wp_upload_dir();
+	$exports_dir = trailingslashit( $upload_dir['basedir'] ) . 'wp-personal-data-exports/';
+
+	/**
+	 * Filters the directory used to store personal data export files.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $exports_dir Exports directory.
+	 */
+	return apply_filters( 'wp_privacy_exports_dir', $exports_dir );
+}
+
+/**
+ * Returns the URL of the directory used to store personal data export files.
+ *
+ * @since 4.9.6
+ *
+ * @see wp_privacy_exports_dir
+ *
+ * @return string Exports directory URL.
+ */
+function wp_privacy_exports_url() {
+	$upload_dir  = wp_upload_dir();
+	$exports_url = trailingslashit( $upload_dir['baseurl'] ) . 'wp-personal-data-exports/';
+
+	/**
+	 * Filters the URL of the directory used to store personal data export files.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $exports_url Exports directory URL.
+	 */
+	return apply_filters( 'wp_privacy_exports_url', $exports_url );
+}
+
+/**
+ * Schedule a `WP_Cron` job to delete expired export files.
+ *
+ * @since 4.9.6
+ */
+function wp_schedule_delete_old_privacy_export_files() {
+	if ( wp_installing() ) {
+		return;
+	}
+
+	if ( ! wp_next_scheduled( 'wp_privacy_delete_old_export_files' ) ) {
+		wp_schedule_event( time(), 'hourly', 'wp_privacy_delete_old_export_files' );
+	}
+}
+
+/**
+ * Cleans up export files older than three days old.
+ *
+ * The export files are stored in `wp-content/uploads`, and are therefore publicly
+ * accessible. A CSPRN is appended to the filename to mitigate the risk of an
+ * unauthorized person downloading the file, but it is still possible. Deleting
+ * the file after the data subject has had a chance to delete it adds an additional
+ * layer of protection.
+ *
+ * @since 4.9.6
+ */
+function wp_privacy_delete_old_export_files() {
+	require_once( ABSPATH . 'wp-admin/includes/file.php' );
+
+	$exports_dir  = wp_privacy_exports_dir();
+	$export_files = list_files( $exports_dir, 100, array( 'index.html' ) );
+
+	/**
+	 * Filters the lifetime, in seconds, of a personal data export file.
+	 *
+	 * By default, the lifetime is 3 days. Once the file reaches that age, it will automatically
+	 * be deleted by a cron job.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param int $expiration The expiration age of the export, in seconds.
+	 */
+	$expiration = apply_filters( 'wp_privacy_export_expiration', 3 * DAY_IN_SECONDS );
+
+	foreach ( (array) $export_files as $export_file ) {
+		$file_age_in_seconds = time() - filemtime( $export_file );
+
+		if ( $expiration < $file_age_in_seconds ) {
+			unlink( $export_file );
+		}
+	}
+}